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NAVEDTRA 14271 Aerographers Mate Module 3 Environmental

1. AU 1 Refractive Index 1 Definition and Symbols of Radar Coded Message Components AIV 1 Reference Wists e655 ox R3 eSB 1 INDEX 1 Nonresident Training Course Follows The Index iii SUMMARY OF THE AEROGRAPHER S MATE TRAINING SERIES The following modules of the AG training series are available AG MODULE 1 NAVEDTRA 14269 Surface Weather Observations This module covers the basic procedures that are involved with conducting surface weather observations It begins with a discussion of surface observation elements followed by a description of primary and backup observation equipment that is used aboard ships and at shore stations Module 1 also includes a complete explanation of how to record and encode surface METAR observations using WMO and NAVMETOCCOM guidelines The module concludes with a description of WMO plotting models and procedures AG MODULE 2 NAVEDTRA 14270 Miscellaneous Observations and Codes This module concentrates on the observation procedures equipment and codes associated with upper air observations and bathythermograph observations Module 2 also discusses aviation weather codes such as TAFs and PIREPs and includes a chapter on surf observation procedures Radiological fallout and chemical contamination plotting procedures are also explained AG MODULE 3 NAVEDTRA 14271 Environmentul Satellites and Wea
2. Max 57 KFT m L 5 KFT 2 FL 1 1 HVE MI SEMI t HOLD 66 DEG OQuEUE 8171353 PUES LIWE CONNECT PENDING Y PAUL ie vti GL M CUAL amp DUNC AGM3F 240 Figure 2 40 Echo Tops ET product Severe Weather Probability SWP Product The Severe Weather Probability SWP product provides an objective assessment of each storm s potential to produce severe weather Unfortunately its sole input is VIL and inaccuracies in VIL values will affect the SWP output Like VIL SWP is a volumetric product that uses vertically stacked grids to calculate severe potential Why then would SWP be any better than VIL SWP grid boxes are much larger than VIL 24 2 x 24 2 nmi Each SWP box contains 121 VIL grids Since SWP analyses more area it builds a larger more reliable picture of each storm and 1 less likely to miss or underestimate them SWP automatically extracts strong convective cells from current reflectivity patterns and estimates their probability to produce severe weather Each convective cell is assigned a number that represents the probability that the cell will develop into a severe storm within 30 minutes By assigning percentage values SWP draws the user s attention to these dangerous cells and provides an objective tool for evaluating
3. adde acm mmc me OR RON THIS PAGE MUST BE PRINTED COLOR PRINTER SS OPTS PEs soe ee ee 09 22 98 18 13 iar 7 59 dee T Zr MEUM MH n i AD WIND ae F 4 E M RIP oca bibe cl nm we HE HB 0 ALLE u 4 22 E 1 8 a 2 35719758H 48 MB E BER 41277 FT 97716740W 35 aH eH RES HE O MODE 11 28 HHHH laLT 39088 FT 26 25 24 KT RME BO LU OL 4 2 _ AE 2 UL do do Ao dH lave CRDA 1915 R 1882 R PROD c 55 RFS KTLX 18 HARDCOPY TIME 1712 1717 ssj ors yes m a __ __ _ 1732 1737 1742 1747 1752 1757 1802 i 5 AGM3F239 Figure 2 39 VAD Wind Profile VWP product r c o U gt Q m c o Ww m 79 5 2 gt r JJ 79 2 m a Storm ID ____ 61 62 02 _ CHIC by E gt E m 3 RAN 292 103 33 64 61 1331 40 POSITIVE POSITIVE POSITIVE HOHE un ub 2 P La B 3H 77424 Ro YW TE i C O00 Lid ie i 3 n n m MODE CNTR
4. AeF Q15 SRM 1752 F PROD UAM ALF KTLA 1757 22 1805 DELTA 575 CAL 8 58 082 HARDCOPY Figure 2 38 Velocity Integrated Liquid VIL product VIL values will change with the seasons and from location to location For instance warm moist air masses exhibit higher VIL values during severe weather occurrences than cooler dry air masses do Therefore the product must be tailored to the area of interest In addition strongly tilted or fast moving storms may produce unrepresentative VIL values VAD Wind Profile VWP Product One of the most useful and unique products generated by the WSR 88D 15 the VAD Wind Profile VWP VAD stands for velocity azimuth display and this program produces current upper wind information on a continuous basis The VAD Wind Profile 15 like having real time rawinsonde data at your disposal every few minutes It shows wind velocities at various altitudes above the earth in 1 000 foot increments up to 70 000 feet fig 2 39 VWP provides easy to read climb winds for pilot briefings The wind plots of VWP are similar to the wind plots on the Skew T diagram and are updated each volume scan VWP depicts environmental flow around the RDA and provides valuable insight into general circulation patterns Be aware that changes in the vertical wind profile are clues to the location of turbulence inversions boundary layers and shear They re also helpful in determining frontal slope
5. directions RADAR BEAM ANTENNA gt a m a gt A am we gt ay gt op AGM3F210 me C um m um ae gt am cm e t am m m tm am me ue om ae m 4 7 gt 7T7 NY incenso T E 2222 AXIS T UCo7k veX 7 24 RN gt IN HALF Tn yonne L POINTS 7 Figure 2 10 Half power points and beamwidth it occupies along the beam at any point in time Unlike pulse length volume does not remain constant While the amount of power within a pulse 15 determined by its length and remains constant power density decreases with distance This occurs because the pulse s fixed amount of energy is spread over a greater area pulse volume as the beam broadens The further a pulse travels the weaker and less effective it becomes due to increased pulse volume RADAR BEAM CHARACTERISTICS The characteristics of a radar beam refer to beamwidth beam broadening and the presence of sidelobes Beamwidth Since EM energy contains properties similar to light it can be pointed and controlled much like a flashlight A suitable antenna can easily focus it into a beam and d
6. 0 7 18 2 255 0 TEMPERATURE 1 18 Figure 1 18 Split enhancement curve 1 18 MB Enhancement 300 300 9 250 250 200 200 9 8 5 150 150 o 5 2 100 7 100 5 50 50 0 050 40 30 20 10 0 10 20 30 40 50 60 70 80 90 100 Temperature C 1 00 3650253 ee orno iomain 2 0 39 292068 sSufaetetueswamcoui 679312 __ widdelevelciouds a 7 3169423 Cmusundemtorms Medgray __ 355 4258533 lt lt 5399594 55 5 3 99 9e 77 926 525545 7 7 Weemom 9 255 255 Wee AGM3f119 Figure 1 19 The GOES MB enhancement curve 1 19 top of figure 1 20 Column 1 is the Universal Coordinated Time UTC and column 2 15 the date of the image The first number in column 3 indicates line stretcher data buffer identification data and the first letter is the satellite identification indicator 5 8 J GOES 9 The second letter in column 3 is the image type which will be either F for full disk IR E for the equivalent IR sector or A B C D for the visible sectors The next number in column 3 15 the resolution in kilometers and the last two letters in 3 COLUMN 1 COLUMN 2 column 3 indicate the type of enhancement curve IR imagery only Columns 4 and 5 are for use by satellite specialists Column 6
7. FFFFFFF Raw perigee 7 decimal places example 5727927 GGGGGGG Raw ascension 7 decimal places example 0 8105893 HHHHHHH Raw inclination 7 decimal places example 02739137 Epoch date in form YYMMDD year month day example 97 03 07 1 36 047 How often should equator crossings ephemeris data be updated for the AN SMQ 11 Q48 Where does ephemeris data for DMSP satellites originate SUMMARY In this chapter we have discussed the various applications of satellite data and some basic terms used to discuss satellite orbits and satellite imagery acquisition We have identified several types of 1 37 environmental satellites and explained the advantages and disadvantages of each We have also discussed the use of various types of satellite imagery and also introduced you to some basic imagery enhancement techniques We described several methods used to acquire satellite imagery and the basic equipment used at Navy and Marine Corps shore stations and aboard ships to receive imagery We also discussed some of the bulletins that provide the orbital data required as input for satellite receiver processors Al A2 4 A7 9 10 11 A12 A13 A14 15 A16 AIT 18 19 20 21 22 23 A 24 2125 ANSWERS TO REVIEW QUESTIONS Zero degrees 0 Geostationary earth synchronous or geosynchronous Ascending node
8. GROUND CLUTTER Another factor affecting radar performance 1 ground clutter Ground clutter 15 an unavoidable form of radar contamination It occurs when fixed objects such as buildings trees or terrain obstruct the radar beam and produce non meteorological echoes Echoes resulting from ground clutter are usually exaggerated in both size and intensity and may cause radar systems to overestimate precipitation intensity near the radar Clutter is normally found close to the antenna where the radar beam 15 nearest to the ground Further out the beam points gently skyward and overshoots most obstacles Under certain circumstances however clutter may exist far away A tall mountain range would be a good example of this The key to dealing with ground clutter 1 operator awareness and experience OTHER FACTORS AFFECTING EM ENERGY As energy travels through space it interacts with millions of scatterers This interaction causes a significant amount of energy to be lost or attenuated ANTENNA AGM3F 217 Attenuation occurs in the form of scattering or absorption but in either case it reduces radar performance The degree of attenuation is dependent on several factors particularly radar frequency and atmospheric water vapor content Scattering Scattering occurs when energy strikes a target and is deflected in all directions fig 2 17 Forward scattering is re radiation of energy away from the antenna and all of this ener
9. The satellite s orbit is synchronized with the movement of the sun across the earth s surface 0200 local Major changes in a satellite s apogee and perigee positions are caused by the shape of the earth and the gravitational pull of the earth sun and moon Atmospheric sounders provide vertical temperature and moisture profiles and atmospheric stability data Geostationary satellites are ideal for making large scale frequent observations over fixed geographical area GOES East Polar orbiting Because of their relatively low altitude orbits polar orbiting satellites provide higher resolution data than geostationary satellites They also provide imagery for the high latitude and polar regions 2 00 km 1500 nmi Fleet Numerical Meteorology and Oceanography Center FNMOC METEOSAT A radiometer The sensor with I kilometer spatial resolution The cold object Longwave radiation Red Sand Infrared imagery is available day and night It is also an excellent tool for oceanographic analysis and is also helpful for identtfiing upper level features White Relatively light gray shades Water vapor imagery produces better definition of the moisture distribution and circulation patterns in the upper atmosphere An enhanced satellite image provides better definition which allows the user to view specific details 1 38 A26 A27 A26 A29 A30 A31 A32 A33 A34 A33 A36 A37 38 3
10. communication network fig 2 25 RADAR DATA ACQUISITION RDA The RDA consists of an antenna and all subcomponents necessary to process backscattered reflected energy into useful radar information The RDA is considered to be the radar s eyes and ears because it provides a detailed snapshot of the radar s surrounding environment It strategically scans thousands of square miles and controls transmission and receipt of all radar energy Any accumulation of data is then passed on to the RPG for in depth analysis Radar Moments Since all atmospheric scatterers provide valuable information the ability to see them is useful in forecasting observing and warning weather customers Obviously we want to see as many of these scatterers as possible The RDA 1s responsible for this detection process The RDA performs signal processing of Doppler weather radar data and transfers this data based upon three radar moments A radar moment is a measurement of a scatterer s reflectivity velocity and or spectrum width at a specific period in time RADAR DATA ACQUISITION UNIT AGM3F225 WIDE BAND RADAR PRODUCT GENERATOR BASE DATA amp DERIVED PRODUCTS PRINCIPAL USER PROCESSOR PUP SUBSYSTEMS Figure 2 25 WSR 88D system configuration REFLECTIVITY Recall some degree of energy is likely to be returned to the antenna as a result of backscattering and that size shape and composition all contribute to a t
11. superrefraction and ducting SUBREFRACTION Occasionally motions in the atmosphere produce a situation where the temperature and humidity distributions create an increasing value of N with height This occurs when density contrast in the atmosphere 1s weak such as when water vapor content increases and or temperature decreases rapidly with height The beam bends less than normal and climbs excessively skyward This phenomenon is known as subrefraction Subrefraction causes the radar to overshoot targets that are normally detected view B Subrefractive conditions are generally rare and usually occur in desert regions and on the lee sides of mountain ranges A NORMAL REFRACTION STE Cor MAT 28 47 2 L1 n z rS ATP EE retta 4 44 ersan PERTE P A gt B SUBREFRACTION ters a UO Mr SUPERREFRACTION D DUCTING 47224 155 F ie I ry J es 4 2 42 PR TAS EEE a Mes Pe 5 t tiv 40 9 4 4 1 42 vr A LH 9 9 vis IM 5 411 50 MM 2 44 EO DC MA 2124 es 2 4224 e 2 2 AGM3F2
12. 01 What are the main advantages of polar orbiting satellites QI2 What is the average swath width of a polar orbiting satellite 013 Which organization is responsible for providing near real tine DMSP environmental imagery to the fleet 014 Which geostationary satellite will provide imagery for Spain and Portugal SATELLITE IMAGERY LEARNING OBJECTIVES Recognize the particular advantages of imagery from geostationary satellites polar orbiting satellites Define spatial resolution radiometer electromagnetic wave and albedo Define the terms visual infrared near infrared and water vapor as they relate to satellite imagery Recognize the advantages of visual infrared and water vapor imagery The pictures or images available from environmental satellites vary depending on the type of satellite and the type of sensor in use Geostationary satellites continuously look at the same geographical area of the earth However the image area is centered on the satellite subpoint on the equator At the subpoint clouds are seen from directly overhead Further away from the subpoint clouds seen in the image are viewed from an angle and feature distortion occurs Cloud cover is often overestimated toward image edges because the sensor is actually viewing the clouds from the side Near the horizon the image 1 considered unusable due to distortion Polar orbiting satellites are in much lower orbits than geostationary sate
13. Our operational overview of these products will include a simple description along with a discussion of the purpose strengths and limitations of each product PRODUCT ACQUISITION Products from the WSR 88D can be grouped into three general areas of application precipitation measurement storm warning and wind profiling These products become available to users 1n one of three ways They are either specifically identified on a routine product set RPS list solicited as a one time request OTR or are automatically generated as an alert condition alert paired product Routine Product Set RPS An RPS list provides an automated way of managing RPG workload It allows associated users to identify and access routinely required products Each PUP site tailors its own list according to mission requirements and modifies this list as needs change via the UCP applications terminal Each RPS list contains up to 20 products catalogued by name and distinguishing characteristics 1 e elevation angle range resolution etc Products found on the RPS list are generated every volume scan and then distributed to the appropriate user One time Request OTR Products that are not routinely needed are not usually placed on the RPS list When such products are needed associated users may obtain them via a one time request All one time requests made by associated users will be honored by the RPG Products not on the RPS list will be
14. Thus the distance to a target can easily be calculated by monitoring a pulse s elapsed time from transmission until its return Half the distance traveled by the pulse determines the target s range from the antenna Pulse Length Pulse length or pulse duration 1 the measurement taken from the leading to trailing edge of a pulse and is a good indicator of the amount of power contained within the pulse 2 7 Generally longer pulses emitted from a radar return more power thus increased target information and data reliability Longer pulses have the disadvantage in that fine details within the return echo may be lost Pulse length 15 usually expressed in microseconds but is also measured in kilometers The WSR 88D incorporates a variable pulse length that may be as short as 1 57 microseconds 1 545 feet Important aspects ofaradar pulse include minimum range range resolution and pulse repetition frequency MINIMUM RANGE Pulse length determines a radar s minimum range or how close a target can get to the antenna without adversely affecting operations Minimum radar range is defined as any distance greater than one half the pulse length In other words targets more than one half pulse length from the antenna can be correctly processed while approaching targets that get too close pose serious problems If targets come within one half pulse length or less of the antenna the pulse s leading edge will strike the target and ret
15. Weather Watch Global Observation System New satellites are routinely placed in orbit to replace older satellites as they wear out and fail Each new satellite usually incorporates new technology and may provide slightly higher image resolution or an entirely new type of sensor As you read this the satellites just mentioned may be out of service and replaced by newer models Information concerning the operational status of all environmental satellites is available via the Internet at the NOAASIS world wide web site operated by NOAA NESDIS This site provides updated position data for geostationary satellites as well as tracking information bulletins for polar orbiting satellites The The WWW Global Observation System C077 27 0 2 USA GOMS 99 Russia 76 Na w GMS gt 8 GOES East en 800 900 USA 75 TUS GOES West Meteor usa USSR 135 gy 7 AGM f109 Figure 1 9 The World Weather Watch Global Observation System site also contains transmission schedules and transmitting frequencies for various United States and foreign operated satellites REVIEW QUESTIONS 07 What is the purpose of a satellite atmospheric sounder 08 What is the main advantage of geostationary satellites Q9 Which GOES satellite provides imagery over all of South America 010 What type of satellite is the NOAA 14
16. form This method 1 only used in rare cases most often used by at sea platforms with little or no environmental satellite reception capability and no Internet access Portions ofreceived images that are of interest to a ship can be extracted compacted encoded for transmission and sent via AUTODIN link to the ship from any other command normally Meteorology and Oceanography centers The AUTODIN encoded images are then available for reprocessing and display by the ship Requests for satellite 1magery via AUTODIN are carried out on a case by case basis Requests should be limited to information that is essential to operations as too much data will slow other AUTODIN message traffic 1 27 REVIEW QUESTIONS Q30 Which U S Government agency provides HF broadcasts of satellite imagery 031 What type of satellite imagery is available from NODDS Q32 How is satellite imagery acquired by most shore based weather stations 33 What is the purpose of a satellite looper 34 What is the advantage of APT direct readout imagery 035 How does the resolution between APT and HRPT data compare 036 What type of information is available from the WEFAX broadcast Q37 What is the fastest way to acquire a wide variety of satellite imagery Q36 How can units with no environmental satellite reception capability or Internet access still receive satellite imagery SATELLITE RECEIVER SYSTEMS LEARNING OBJECTIVES Identify the two p
17. thermal advection and the evolution of jet streams Different colors are used to indicate the reliability of the wind data For instance green wind barbs indicate that plenty of scatterers were available at that particular azimuth and elevation thus highly accurate wind values are displayed VWP 1 unique in that the mere absence of data plotted as ND can itself be an indicator It suggests fewer scatterers which implies dryer air common behind cold fronts This same technique also allows operators to view changes in overall cloud coverage above the radar s viewing area REVIEW QUESTIONS Q56 Products from the WSR 88D are grouped into what three areas of application Q57 What is the purpose of the Routine Product Set RPS list Q58 What is the purpose of an alert paired product Q59 What does the Base Reflectivity product REF display Q60 hook echo signature is associated with what phenomena 061 What does the color blue represent on the Base Velocity product VEL Q62 Velocities from the Base Velocity product VEL are relative to what major component of the WSR 68D Q63 What is the most serious drawback to the Composite Reflectivity CR product Q64 What is the primary purpose of the Vertical Integrated Liquid VIL product Q65 What might lack of data indicate when using the VAD Wind Profile VWP product Echo Tops ET Product Echo Tops ET is yet another specialty product
18. 1s often called bearing or directional resolution It is a radar s ability to display side by side targets correctly Azimuthal resolution 1s controlled by beam width as only targets separated by more than one beamwidth can be displayed separately As the radar antenna rotates targets too close together occupy the beam simultaneously This causes them to be displayed as one wide target stretched azimuthally sideways Since azimuthal resolution depends on beamwidth which changes with distance targets near the antenna require less separation than those further out Near the antenna a narrower beam allows the radar to recognize tighter gaps and display targets separately At greater distances more separation is required If targets are not separated by the prescribed amount distortion occurs and resolution suffers With the WSR 88D azimuth distortion is approximately 1 mile at a 50 nmi range Thus at 250 nmi two targets must be about 5 miles apart before they will appear as two separate targets MAIN BEAM AGM3F212 Figure 2 12 Radar sidelobes In notice that targets located at position A are more than one beamwidth apart The radar therefore displays them correctly as two separate echoes Also notice that some degree of stretching 1s evident in both echoes due to partial beam filling Targets located at position B are exactly one beamwidth apart and are displayed as one large echo As the beam rotates there 15 no bre
19. 270 The WSR 88D views the full component and measures all 20 knots AGM3F222 Motion Diagonally Across Radial Axis When a parcel s motion becomes diagonal to the radial axis only some portion of its phase shift 1s observed Since less than maximum motion is realized an underestimation of target speed is plotted and displayed The degree of error depends entirely on the parcel s angle and orientation In figure 2 21 component B the wind is still blowing from the west at 20 knots but the antenna is pointing toward 315 Only a portion of the wind is blowing directly toward the antenna and the WSR 88D measures only 15 knots Motion Perpendicular to Radial Axis Since the radar antenna rotates in a full circle 360 the parcel s orientation to the beam axis 1s ever changing At some point the parcel s motion becomes perpendicular to the radial and exhibits zero motion toward or away from the antenna component C This does not necessarily mean that the target 1 stationary It simply means that the target 1 remaining at a constant distance from the radar and because of the radar s perpendicular viewing angle no phase shift 1 observed As far as the radar 15 concerned the return pulse remains unchanged and no phase shift has occurred From this information the parcel is considered stationary Zero velocity is displayed while the parcel s actual speed goes undetected In the following text we will show how the WSR
20. FM NAVSPASURCEN DATA DAHLGREN VA TO USS NOBODY BT UNCLAS N03840 SUBJ SATELLITE EQUATOR CROSSINGS ASC EQUATOR CROSSINGS FOR SATELLITE 16969 NOAA 10 ALT KM INCLINATION NODAL PERIOD NODAL INCR 810 98 59575 101 2068 25 30 HRMNSE LONG DAY YR REV 071511 011022 86 6W 169 97 19473 gt Orbit of first crossing 025134 111 9W Consecutive day Julian day and year of first orbit 043246 137 2W 061359 162 5W 172 2 Ascending node equator crossing longitude 4Ascending node equator crossing time hours minutes seconds UCT Message continues with equator crossing times UCT and east west longitudes for several crossings and then provides similar information for many other satellites 1 35 Table 1 7 C Element Orbital Data Message ZNR UUUU 0417277 MAR 97 FM NAVSPASURCEN DAHLGREN TO XXXXXX BT UNCLAS N03840 16969 2907047 8352017 99938 0013459 5727927 8105893 2739137970307 16969 2907047 8352017 99938 0013459 5727927 8105893 2739137970307 16969 2907047 8352017 99938 0013459 5727927 8105893 2739137970307 19531 0665307 8281567 99929 0011969 5853780 5828128 2749230970307 19531 0665307 8281567 99929 0011969 5853780 5828128 2749230970307 19531 0665307 8281567 99929 0011969 5853780 5828128 2749230970307 21263 3456862 8339169 00000 0068626 5838341 3961844 2740511970306 21263 3456862 8339169 00000 0068626 5838341 3961844 2740511970306 21263 3456862 8339169 00000 0068
21. In addition to the automatically generated remarks Part C provides for optional manual entries Appendix III provides a listing of definitions and symbols that are routinely used in the remarks section REVIEW QUESTIONS Q66 What do the plotted heights on the Echo Tops ET product indicate Q67 What is displayed on the Severe Weather Probability SWP product Q68 What is a mesocyclone Q69 The Tornadic Vortex Signature TVS product is derived from what data Q70 How long will the Storm Track Indicator STI product track an individual storm 071 What information does the Hail Index product provide Q72 What is the primary purpose of the Reflectivity Cross section RCS product Q73 How could the Reflectivity Cross Section RCS product be useful to an observer Q74 What information can be obtained from the Vertical Cross Section VCS product in clear air mode 072 What does the symbol ZR indicate in a Radar Coded Message WSR 88D PUBLICATIONS LEARNING OBJECTIVE Identify the publications associated with the WSR 88D system 2 55 The Federal Meteorological Handbook No 11 FMH 11 Doppler Radar Meteorological Observations 1 the governing manual for Doppler weather radar observations and consists of four parts Part A System Concepts Responsibilities and Procedures explains the overall concept of the WSR 88D program and details site responsibilities and outlines general procedures It
22. RRRRRRRR 5555555555 UUUUUUUUUU 26324050 07228814 P052955506 M049302836 M000000000 VVVVVVVVV WWWWWWWWW XXXXXXXXX YYYYYYYYY ZZZaaabbb M00803903 M00840889 07331793 004218509 104094004 9449 dddddddddd eeeeeeeee ggggggggg hhhhhhhh LoLoLolololololo 0000500000 M00272363 P00100495 P00508212 19428046 13702451 102897 M00110 121597 M00700 120197 P00010 032498 APT TRANSMISSION FREQUENCY 137 62 MHZ HRPT TRANSMISSION FREQUENCY 1707 0 MHZ BCN BEACON DSB FREQUENCY 137 77 MHZ APT DAY NIGHT 2 4 VIS CH 2 0 725 TO 1 0 AND IR CH 4 10 5 TO 11 5 XMTD DURING S C DAY IR CH3 3ND IR CH 4 10 5 TO 11 5 XMTD DURING S C NIGHT DCS CLK TIME YR DA TIM 1995 021 79186 656 BT shows a typical TBUS bulletin with the information in Parts II and III deleted We have added a symbolic code form in italics to help you understand what information is included in the message Table 1 3 references this symbolic code form and identifies the information We have concentrated on the information needed for input to the various ephemeris update programs currently in use Appendix II is a diagram of the octants of the globe 1 32 Directly under the APT Predict line is an identifier for the date of the beginning of the prediction period and the U S satellite identification number In our example in the table 0105038 means the prediction period begins on January 05 0105 for satellite 38 NOAA 14 The orbital predictions are carri
23. TBUS bulletin See table 1 7 for an example of a typical message containing C element orbital data and table 1 8 for an explanation of the data In the C element orbital data message each line of data is repeated three times This is done so that Table 1 4 Sample NASA Two line bulletin NOAA 14 1 234550 94089A 95222 82483495 00000053 00000 0 53646 4 0 2755 2 23455 98 9047 164 9161 0010620 42 0812 318 1174 14 11526152 31526 1 34 Table 1 5 Explanation of NASA Two line bulletin elements Satellite name 1 Message line 1 23455 Satellite number 23455 94 Launch year 1994 NOAA 14 23455U 94089A A Launch piece A not in multiple pieces 95222 82483495 95 Epoch year 1995 222 82483495 Julian day 222 and fraction 00000053 089 Launch number 89 First time derivative of the mean motion decay rate 00000 0 Second time derivative of the mean motion 53646 4 BSTAR drag term Ephemeris type zero Element number 275 5 Check sum 2755 2 Message line 2 i 2 23455 223455 Satellite number 23455 repeated 989047 7 Orbit inclination 989047 degrees 00000000 164 9161 Right ascension of ascending node 164 9161 degrees 4208122 Argument of perigee 042 0812 degrees S 31526 3152 Satellite revolution 3152 at epoch 6 Check sum H h Table 1 6 A Portion of a NAVSPASURCEN Satellite Equator Crossings Message
24. This includes time required to resubmit failed assignments PASS FAIL ASSIGNMENT PROCEDURES If your overall course score is 3 2 or higher you will pass the course and will not be required to resubmit assignments Once your assignments have been graded you will receive course completion confirmation If you receive less than a 3 2 on any assignment and your overall course score is below 3 2 you will be given the opportunity to resubmit failed assignments You resubmit failed assignments only once Internet students will receive notification when they have failed an assignment they may then resubmit failed assignments on the web site Internet students may view and print results for failed assignments from the web site Students who submit by mail will receive a failing result letter and a new answer sheet for resubmission of each failed assignment COMPLETION CONFIRMATION After successfully completing this course you will receive a letter of completion ERRATA Errata are used to correct minor errors or delete obsolete information in a course Errata may also be used to provide instructions to the student If a course has an errata it will be included as the first page s after the front cover Errata for all courses can be accessed and viewed downloaded at http www cnet navy mil netpdtc nac neas htm STUDENT FEEDBACK QUESTIONS We value your suggestions questions and criticisms on our courses If you would
25. are color coded while wind directions are not Cooler colors such as blues and greens depict velocities moving toward the antenna negative values Conversely warm colors red orange yellow are outbound positive values Gray colors indicate where the wind component is perpendicular to the radial direction from the radar zero velocity Determining the wind direction from Base Velocity data can be difficult and requires practice Look figure 2 36 View A shows a vertical profile of uniform wind speed that veers with height View B depicts the same general wind field as it Lead HEIGHT 0 ao 135 180 270 DIRECTION DEG a4 HEIGHT 0 JD 40 60 SPEED KT A VERTICAL WIND PROFILE TOWARD NEGATIVE VALUES ZERO DOPPLER VELOCITY LINE C BASIC INTERPRETATION OF DISPLAY D DOPPLER VELOCITY DISPLAY Figure 2 36 A Vertical wind profile B Horizontal wind profile C Basic interpretation of display D Doppler velocity display would appear in the horizontal View C is a basic interpretation of wind direction along the zero Doppler line where the small arrows represent wind vectors The orientation of the zero Doppler line in this figure indicates the wind direction is perpendicular to the radar beam at that particular azimuth For example along the outer edge of the display the velocity is zero when the radar beam points to the north point 1
26. built on demand With NAPUPs however this 1s not the case Since non associatedusers cannot increase the RPG s workload new or unusual products are NOT built on demand for them OTRs made by NAPUPs are only honored for pre existing products stored in the RPG database Alert paired Product The WSR 88D 15 capable of producing alert messages accompanied by audible alarms Such alarms are sounded at each PUP site when prescribed conditions occur Alert criteria are usually based upon severe weather parameters alert conditions are user definable and should be established jointly since they affect each user of an associated RDA Once criteria are established at the UCP selected products known as alert paired products will be transmitted automatically with each alert These products aid in severe weather evaluation Each PUP site receives both the alert message and any alert paired products This eliminates the need for one time requests and allows forecasters to assess the situation rapidly Alert messages and alert paired products are given the highest priority by the system Significant weather events may be missed under certain circumstances Thus alert paired products reduce the potential of operator oversight resulting from poor product selection Alert paired products might mean the difference between ample warning of severe weather or no warning at all For example 50 knot winds will trigger an alert a base velocity pro
27. cases the signal processor compares mystery echoes to energy received from beyond the radar s displayable range Through pattern matching it determines the likelihood of each target s true existence or the probability that such targets are a result of range folded data If range folding is confirmed false echoes are removed from products If the processor is unsure suspect areas are shaded purple This purple area is easily recognized and alerts you to the possibility of range folding When preprocessing is complete data 15 transmitted to the RPG LEG M EN BMAF 22 Figure 2 28 WSR 88D Radar Product Generator RPG 2 26 GROUND CLUTTER FILTERING The process of reducing the effects of ground clutter begins as the data radar returns received at the RDA leaves the RDA s signal processor A ground clutter suppression algorithm is then applied This algorithm is designed to suppress power reduce reflectivity from echoes that return a lot of energy but are not moving buildings trees etc Two clutter suppression maps are created during this process one map is used by the RDA to determine which echoes are of a permanent nature buildings trees and a second map that is used by the operator to select areas for specific clutter suppression Once built these maps can be referenced by the radar to apply suppression to clutter that has been identified with each new scan of the radar Obviously this process increases pr
28. change or deviation from a perfectly stable orbit Some anomalies are planned into an orbit so that the orbit will remain sun synchronous as earth revolves around the sun during the course of a year Anomalies further complicate satellite orbital predictions REVIEW QUESTIONS Ol A satellite with an equatorial orbit would have an inclination angle of how many degrees Q2 What term is used for a satellite with an equatorial orbit moving with the same speed and direction as the earth Q3 What term is used to describe the period of time when a polar orbiting satellite is traveling south to north Q4 What is meant by the term sun synchronous satellite Qs lfa satellite has an ascending node time of 1400 local what would be the approximate descending node time at the same location Q6 What are the major factors that would cause changes in a satellites apogee and or perigee position TYPES OF ENVIRONMENTAL SATELLITES LEARNING OBJECTIVES Recognize the various functions performed by environmental satellites Identify the major satellite programs operated in the United States Identify specific types of geostationary satellites polar orbiting satellites DMSP satellites foreign satellites Recognize the advantages and disadvantages of geostationary and polar orbiting satellites The first meteorological satellite was launched in April of 1960 and was known as TIROS 1 Television and InfraRed Observation
29. depends largely on distance Narrowband Narrowband consists of a series of dedicated telephone lines that link all remaining components PUPs to the RPG refer back to It is primarily used to disseminate products to users and relay UCP commands to the appropriate radar component Narrowband also carries message traffic between the UCP operator and system users If a single narrowband link becomes disabled only that specific user PUP is affected Since dial in capability exists impact to the user is minimal AII access ports on the RPG are designated as either dedicated for APUPs and PUPS or dial in for part time users NATIONAL WEATHER RADAR NETWORK NWRN The National Weather Radar Network NWRN is a composite of WSR 88D sites from around the country Each site 1 tasked with the challenge of continuous collection of radar data while ensuring the availability of WSR 88D products to all system users Currently this network consists of over one hundred sites providing nearly complete coverage of precipitation and severe weather events throughout the us The NWRN increases the WSR 88D s versatility and establishes greater flexibility for system users The NWRN allows users to access far away sites providing live data for aircrew briefings and other types of mission support Connections are made via commercial phone lines therefore access to a remote site defines you as a non associated user NAPUP Once contact 15 termin
30. environmental satellite and weather radar Student Comments Course Title Aerographer s Mate Module 3 Environmental Satellites and Weather Radar NAVEDTRA 14271 Date We need some information about you Rate Rank and Name SSN Command Unit Street Address City State FPO Zip Your comments suggestions etc Privacy Act Statement Under authority of Title 5 USC 301 information regarding your military status is requested in processing your comments and in preparing a reply This information will not be divulged without written authorization to anyone other than those within DOD for official use in determining performance NETPDTC 1550 41 Rev 4 00 1X CHAPTER 1 ENVIRONMENTAL SATELLITES INTRODUCTION Satellite images or pictorial representations of satellite sensed information are some of the most frequently used tools in the fields of meteorology and oceanography As a Navy or Marine Corps observer one of your primary duties will be to acquire satellite imagery You may also be required to process the imagery to better display features of interest to the analyst Later as you begin to analyze meteorological and oceanographic situations you will use satellite imagery as one of your most important sources of information In this chapter we begin with an explanation of some of the basic terminology used to describe satellite orbits and satellite tracking Next we introduce environmental satellit
31. extrapolate movement of features Products may be stored locally on the PUP s hard disk or sent to the printer for a color hard copy PUPS are connected to the RPG via a narrow band ordinary telephone lines Like other components PUPS may be geographically separated from the host system RDA RPG by many miles minimum of one PUP must exist to constitute a complete system However since the WSR 88D is designed to support several users numerous PUPS can be configured to access a single RPG the actual number of users varies Each PUPS distance from their respective RPG depends solely on their geographical location Common PUP sites include military installations National Weather Service forecast centers Federal Aviation Administration airport offices and the Air Force Weather Agency AFWA to name a few PUP hardware includes the following AGM3F229 Figure 2 29 WSR 88D Principal User Processor PUP e Two 19 color graphic monitors that are used to display products in full or 1 4 screen mode e A graphic tablet and puck that are the primary input devices used to make product selections or request actions of the PUP processor The graphic tablet s surface is flat and is organized as color coded work areas The puck is a mouse like device that acts as a hand held pointer to invoke desired processor commands e A color graphics printer that provides hard copies on demand e A processor that computes or executes
32. have an important effect on radar effectiveness Wavelength plays a critical role a weather radar s ability to see scatterers that 1s water droplets Shorter wavelengths provide more detail and allow detection of small droplets while longer wavelengths are best for larger targets such as precipitation from showers and thunderstorms It is important that a radar wavelength 360 4 WAVELENGTH gt V CREST 1 14 204 360 Figure 2 4 Wavelength of an electromagnetic wave 2 3 be short enough to detect fine scatterers without sacrificing severe weather detection abilities Amplitude Wave amplitude 1 simply the wave s height from the midline position and represents the amount of energy or power contained within the wave Simply put greater amplitude means more power Amplitude V NN expressed as some fraction of a meter 2 5 Frequency Frequency refers to the number of completed wave cycles per second Radar frequency 1 expressed in units of hertz Hz one hertz being equal to one cycle per second Frequency and wavelength are closely related as a change in one has a direct impact on the other Essentially higher frequency transmitters produce shorter wavelengths and lower frequency transmitters produce longer wavelengths All wave characteristics in some way affect radar power When more energy is avai
33. lower minimum temperature will appear white Areas warmer than the higher maximum temperature will appear black Areas which are temperatures between the upper and lower ranges will appear gray Predefined Enhancement Curves Besides locally developed enhancement curves there are several predefined enhancement curves available for GOES imagery that have been tested and evaluated over many years Each of these enhancements was developed for a specific application One of the most common 15 the MB Curve This is a very good all purpose curve but was specifically designed for summertime convective activity The MB curve has very distinct contours thresholding around specific temperatures and 15 especially helpful in picking out thunderstorms shows the configuration of the MB curve The GOES User s Guide contains detailed information on various predefined enhancement curves Visible imagery can also be enhanced by adjusting brightness values vice temperature values as with IR imagery Enhanced visible imagery 15 especially useful in cases of fog and thick stratus GOES LEGEND INFORMATION Much information about a particular GOES satellite image 1s available from the GOES legend that appears at the top of each image received over the GOES Telecommunications Access Program GOES TAP An example of a GOES legend is shown at the COUNT VALUE INPUT 100 G R A Y S C A L E 443 6 8 280 0 150 ACVACO mcr Azcoo
34. may be recognized The known phase of the transmitted signal allows measurement of the phase of the received signal The Doppler shift associated with the echo from which the return originated is calculated from the time rate of change of phase The phase of a wave measured in degrees where 360 degrees equals one wavelength indicates the current position of the wave relative to a reference position For example look figure 2 18 At time view A the position of the wave along the vertical line was as shown while at time T2 view B the position of the wave along the vertical line was as shown Notice that the wavelength did not change from T1 to T2 However the wave s position relative to the vertical line changed 1 4 wavelength or 90 degrees This change 15 the phase shift AGM3F218 Figure 2 18 Wavelengths and phase shifts A T I is wave reference position B T 2 wave s position has changed 90 from reference position 2 17 RAP qt AGM3F219 Figure 2 19 A Stationary target causing no visible change in wave characteristics B Moving target displacing energy causing observable phase shifts As another example look at figure 2 19 view A Imagine a Doppler radar repeatedly striking a stationary target such as a building Since the speed at which energy travels is constant each wave returns in exactly the same phase as those before it Now look at view B Consider a large ball
35. nice to have it should be routinely verified using VIL and VEL Reflectivity Cross Section RCS Product Cross sections provide a unique perspective of the atmosphere They create an illusion that places you the operator into the heart of a target This allows you to view meteorological targets such as mesocyclones from the inside Cross section products can be built from any of three radar moments reflectivity velocity and spectrum width and are primarily used to examine vertical storm structure All cross section products operate on essentially the same principle That is they allow a vertical depiction of the atmosphere by compiling base data vertically along a user defined direction Data from a cross section product is presented in a range up to 124 nmi versus height up to 70 000 feet format The Reflectivity Cross Section RCS product is helpful even during nonconvective events The depth of moist layers can be determined by the vertical extent thickness of scatterers When cross sections are cut across frontal boundaries frontal slope can be determined For observing purposes RCS is a good tool for measuring cloud bases and tops and inversion boundaries Clouds generally appear as well defined layers with a significant decrease in energy dBZs at the cloud s edge Of course RSC is very useful when evaluating severe weather potential It permits three dimensional analysis of storm dynamics and lets you determi
36. of the GOES legend indicates the sector identification of the image The term sector refers to the segments of a GOES image that are expanded or contracted to the desired geographic region of a particular GOES TAP distribution site The first letter indicates the satellite field distribution site for which COLUMN 4 COLUMN 5 COLUMN 6 Figure 1 20 A GOES 8 infrared sector taken at 2145 UTC June 21 1995 The GOES legend is at the top of the image 1 20 the sector was generated such as D for Washington D C or S for San Francisco The next letter indicates the sector resolution in kilometers that is A 1 km 2 km C 2 4 km and D 8 km IR only The last digit indicates the identification number of the specific sector GOES TEMPERATURE SCALE The temperature scale appears only on IR and WV imagery and it appears below the legend The temperature scale 1s divided into 10 increments with a range from 50 C to 100 C It has 15 temperature blocks separated by white or black vertical lines The temperature scale is very useful in cloud and non cloud identification REVIEW QUESTIONS What is the purpose of enhancing satellite imagery 025 026 What is major disadvantage of providing too much definition to user defined enhancement curves Q27 Which type of user defined enhancement curve applies two complete gray shade and count value scales for two separate temperature ranges What is i
37. over many years linked a number of weather events with the signatures they produce Classic radar signatures are often the key to identifying severe weather potential before it occurs Some of the more important signatures are briefly discussed here HOOK ECHO The hook is a pendant shaped echo resembling the figure 6 It is produced by precipitation being wrapped around a vortex Therefore hooks are typically associated with tornadoes The hook 1 not the actual tornado 1t 1s merely an indicator The right rear quadrant of a storm with respect to storm movement is the best place to monitor development since tornadoes commonly SoC j T o U gt Q m c o i m U 2 m gt Q O 2 0 2 2 m 2 Figure 2 32 Base Reflectivity product go 25 89 23 53 BASE REF 19 R 238 KM KM RES 03 26 89 02 27 PDA KOUN 35 14 1255 FI a ELEU 1 5 MODE 11 ADEG 63 DBZ lt TH DBZ 5 13 18 23 28 33 38 43 48 53 58 63 68 73 gt 75 1 FL 1 FM 3M A c AGMGF232 form there Figure_ 2 33 Jexhibits a classic hook signature Hook detection is difficult under any circumstances Hooks are a small short lived feature often obscured by surrounding storm mass Due to beam broadening distant hooks might be missed altogether While the vertical extent of a tornado might exceed 35 000 feet hooks
38. symmetry tests required for mesocyclone classification The shear area 15 not balanced or uniform 3 D shear is termed correlated shear because of its vertical link MESOCYCLONE This category identifies shear regions that meet all algorithm requirements of size shape symmetry and vertical consistency associated with a mesocyclone MESO like any product is just a tool It should NEVER be used as a stand alone source of information and its findings should always be confirmed with other products such as VEL Although velocity data is processed up to 124 nmi from the RDA the optimum effective range of this product 1s severely restricted by beam broadening The mesocyclone detection algorithm does not establish time continuity this is left up to the operator Figure 2 42 8 an example of the MESO product It indicates that a single mesocyclone large circle has been identified just northwest of the station Tornadic Vortex Signature TVS Product Just as with the MESO product the Tornadic Vortex Signature TVS algorithm performs extensive reanalysis of base velocity data to build each TVS product This product is designed to search out tornadic signatures within mesocyclone bearing storms The TVS product is a small area of abnormally high shear commonly associated with tornadoes Like mesocyclones TVSs are first detected at the storm s mid section and grow both up and downward with time They reach cloud bases coincide
39. the VIL algorithm holds many similarities to composite reflectivity It builds a volumetric product by compiling reflectivity data from all elevation angles The difference 1 that VIL displays tallied values for the entire column fig 2 38 CR displays only the reflectivity maxima regardless of altitude Users can quickly evaluate storms by comparing VIL columns VIL 1 useful when monitoring general echo pat terns for signs of development In convective situa tions VIL 1 directly related to updraft strength which translates into storm severity The VIL product was designed to distinguish severe from nonsevere storms but it 1s also used as a hail indicator very high 4845 Ic THIS PAGE MUST BE PRINTED ON A COLOR PRINTER 82 1690 02 18 REF 37 CR 238 KM 4 RES 8 9781 789 23 38 357147 89H 1255 97727743W MODE 11 ak H Max 68 082 lt TH DBZ B 13 18 23 28 33 38 43 48 53 38 63 BS 73 EN gt 75 1 FL 1 COM 1 OUL AT OUL HI 51 AYR 79 DEG 96 KM QUEUE EMPTY UP 16 0120 GRAPHICS J PU TW ea RESET 4 MAT HARDCOPY HARDCOPY FEGQUES ACCEPTED AGM3F237 Figure 2 37 Composite Reflectivity CR product crc THIS PAGE MUST BE PRINTED ON A COLOR PRINTER 22 98 18 95 4 INT 190 57 ul 70 w 4 FL 1
40. them SWP can be displayed alone but 15 best used as overlay on other products perhaps VIL or Base Reflectivity REF Figure 2218 an example of the Severe Weather Probability product SWP data is calculated from VIL and ultimately base reflectivity Therefore SWPs are affected by all of the same factors that affect VIL and REF Mesocyclone MESO Product Mesocyclones are areas of strong cyclonic rotation found in supercell thunderstorms Such storms are normally accompanied by severe weather although not all mesocyclones produce tornadoes The WSR 88D uses extensive computer processing of velocity data to build an extremely valuable product called MESO mesocyclone The algorithm continuously searches for rotating wind fields produced by areas of strong shear Shear is a speed and or directional variation in the wind field with height The algorithm is designed to identify three types of shear and categorize them accordingly 2 D shear 3 D shear or mesocyclone 2 D SHEAR This is an area of horizontal rotation that meets the algorithm s shear and symmetry tests Symmetry determines the area s balance and uniformity 2 D shear lacks vertical consistency It 1 only found at one elevation angle and cannot be linked 2 46 at adjacent levels For this reason 2 D shear is said to be uncorrelated shear 3 D SHEAR 3 D shear has vertical consistency and can be linked to other elevations However 3 D shear fails the
41. value of 28 4 is the difference between 103 4 and 075 09 ignoring the sign The antenna elevation 1 about 48 degrees and the azimuth on the NW scale is 126 degrees INTERNET In recent years the Internet has become a very efficient method of acquiring satellite imagery The worldwide web is the fastest way to acquire a wide variety of real time satellite imagery NOAA NEDSIS has its own website NOAASIS along with several private companies and universities Of particular importance is that these sites can be reached aboard ships equipped with Internet access FNMOC can also transmit satellite imagery over the military Internet NIPRNET and SIPRNET This imagery can then be viewed using Joint METOC Viewer JMV software with any computer system able to process the data Details on the JMV and the NIPRNET SIPRNET routing networks is covered in later modules The Naval Research Laboratory in Monterey California has an outstanding Internet homepage that provides a tremendous amount of satellite imagery data It contains general information relating to environmental satellites and provides guidance packages for new and experimental satellite products The website also provides links to various other satellite imagery sources AUTODIN MESSAGE The Automatic Digital Network AUTODIN is the U S Navy s most common method of transmitting message traffic between commands Satellite images can also be sent via AUTODIN in greatly compacted
42. you experience Doppler shifts many times each day The change in pitch of a passing train whistle and a speeding automobile horn demonstrate its effects When you hear a train or automobile you can determine its approximate location and movement Doppler radar accomplishes much the same thing but to a higher degree of accuracy As a target moves toward a radar frequency is increased if the target is moving away from a radar the frequency is reduced The radar then compares the received signal with the frequency of the transmitted signal and measures the frequency shift giving the motion and speed of the target While frequency of electromagnetic energy 15 modified by moving targets the change is usually too slight to measure precisely Therefore Doppler radar focuses on the phase of electromagnetic energy as this aspect experiences a greater degree of displacement and increases the likelihood of detecting motion Using phase shifts instead of frequency changes can be compared to viewing an insect under a magnifying glass Features that might otherwise go unseen take on a new dimension and become observable PHASE SHIFT The phase of a wave 1 a specific point or benchmark along that wave A phase shift 1 an observable repositioning of this benchmark between successive transmissions A pulse Doppler radar in its simplest form provides a reference signal by which changes in the frequency phase of successively received pulses
43. 15 Figure 2 15 A Normal refraction B Subrefraction C Superrefraction D Ducting SUPERREFRACTION If the atmosphere s temperature increases with height inversion and or the water vapor content decreases rapidly with height the refractivity gradient will decrease from the standard table 2 1 This situation is known as superrefraction and causes the radar beam to deflect earthward below its normal path view C Generally radar ranges are extended when superrefractive conditions exist However some targets may appear higher on radar than they would under standard atmospheric conditions 2 13 Table 2 1 Refractive Conditions as a Function of N gradient Refractive Condition N gradient lt 48 N thousand feet 2 157 N thousand meters 48 to 24 N kft 157 to 79 N km 24 to 0 N kft 79 to 0 N km Ducting Superrefractive Standard Superrefraction occurs under strong inversions which are typical subtropical high pressure zones DUCTING In extreme cases a very rapid decrease in the N gradient will cause radar waves to become trapped in a layer of the atmosphere and travel abnormally long distances table 2 1 This phenomenon is known as ducting and 1 a frequent occurrence when strong inversions are present When ducting occurs a returning pulse may display low targets from hundreds of miles away targets that are not normally detected view D This may
44. 243 62715796 18 33 61 TUS 18 23 41 52 04 72 44 28 04 30 78 ELA 62 FT DE ZELE 1 1585 1 QUL NUL Lew ST ENFTY HRR COPY HARDCOPY REQUEST 30 RCCEPTED Figure 2 43 Tornadic Vortex Signature TVS product independently and determines whether the product will forecast an entire hour s movement a 45 30 or 15 minute movement or simply omit a forecast for any given storm Up to 100 storms may be monitored simultaneously If a storm s motion exceeds certain thresholds the STI algorithm may become confused It bases forecasts on linear extrapolation of past movement Therefore storms traveling in a curved path or changing direction will not be accurately forecast STI is intended for well defined isolated thunderstorms Under any other circumstance 1 squall lines LEWPs etc the algorithm becomes confused resulting in a questionable product If storms have crossing paths or are in close proximity to one another 2 49 the algorithm might misidentify them and in extreme cases identify them as a single storm Hail Index HI Product The Hail Index HI product scans all storms within the radar coverage area and searches for very high reflectivity values located above the freezing level It then provides an indication of which storms are expected to produce hail All storms are examined for hai
45. 42 157 HARDCUPY t 7C THIS PAGE MUST BE PRINTED ON A COLOR PRINTER AGM3F 246 ALT KFT MAX 710 2 ALT e4KFT gt 19297 41 Figure 2 46 Reflectivity Cross Section RCS product amp SECT REF 58 RCS 83 21791 21 18 35 12 23H 1266 3 7 7 1 D a E 1 1 197 21 HM 1 QUEUE 2171451 ARCHIVE UNIT 1 READ DONE Hee LIU REEL C fl 885 ida vec I o U gt c o 00 m U m gt r JJ U 2 m 9 T DAR MIN 66kT ALT 48KFT ALT KEY lt 5 D 2 ___________ _________ _ e i Oo awe My 271 X SECT 1 a E 1 e Il MODE 1 1 1 ed RF FL 1d is na Jim Tu E 1 COMzI ee 2171451 UNIT 1 READ DONE Ay _ 28 2 ip I AaZ RD 17 4 gt lt 168 683162 69 Figure 2 47 Velocity Cross Section VCS product bene Geena 1 ARCHIVE PE OLE CI92 586 ida mesocyclones centroids storm tops and hail indices are all automatically generated
46. 626 5838341 3961844 2740511970306 BT any hits on the signal during transmission may be REVIEW QUESTIONS detected and corrected by the user Because of this 042 What is the purpose of ephemeris data format the message is sometimes called 3 line Charlie 043 What are the most common methods of data The periods separate individual data elements obtaining TBUS data and in most cases indicate a decimal point mE 044 What information is contained Part I of the Be aware that the NAVSPASUR assigned TRUS Gergen identification numbers do not correspond to either U S a satellite numbers or to the international satellite 045 What general information is contained in Part identification The Satellite Equator Crossings IV of a TBUS message message provides both NAVSPASURCEN s satellite number and the satellite name such as 21263 NOAA 046 What is the second element of a NASA Two line 12 message Table 1 8 Format of C Element Data C ELEMENT DATA LINE AAAAA BBBBBBB CCCCCCC DDDDD EEEEEEE FFFFFFF GGGGGGG HHHHHHHIIIIII 16969 2907047 8352017 99938 0013459 5727927 8105893 2739137970307 ELEMENT INTERPRETATION AAAAA NAVSPASURCEN Satellite number example 16969 BBBBBBB Raw mean anomaly 7 decimal places example 0 2907047 CCCCCCC Raw mean motion 7 decimal places example 0 8352017 DDDDD _ Raw orbital decay 5 decimal places example 0 99938 EEEEEEE Orbital eccentricity 7 decimal places 0 0013459
47. 88D deals with this problem VELOCITY ALIASING Imagine two trains connected back to back Since trains have the unique ability to go full speed in either direction their orientation poses no problem Notice the method that trains use to display speed fig 2 22 Figure 2 22 Train speedometer 2 19 Forward speeds are on the right half of the speedometer while reverse speeds are on the left Speeds of less than 50 mph are clear cut unambiguous and cause no confusion However speeds of 50 mph or more are ambiguous and cause a phenomenon known as velocity aliasing Velocity aliasing 1s a process that causes a Doppler radar to display untrue velocity values because of the motion of the target Consider the following scenario A train departs the station traveling forward at 40 mph view A Beyond city limits its cruising speed is increased another 20 mph view B Suddenly something is wrong The speedometer reads 40 mph in reverse The train did not change direction it has simply exceeded the limits of its instrument The train s speed appears aliased as 40 mph in reverse obviously an ambiguous velocity While radars don t use speedometers they do measure phase shifts and experience velocity aliasing in much the same way as the train Consider the 360 of one wavelength as the radar s speedometer When phase shifts are less than 180 one half wavelength they are clearly detectable However shifts of 180 or more a
48. 9 40 41 42 A43 A44 A45 A46 A47 48 Too much definition in an enhancement curve may make the the imagery difficult to interpret A split enhancement curve Sector identification information 10 U S Coast Guard DMSP The GOES TAP system A satellite looper stores and displays a series of satellite images over the same area which in turn shows the movement of cloud and weather systems APT satellite transmissions provide real time data and are relatively inexpensive to obtain APT is at I kilometer resolution and HRPT is at 1 kilometer resolution Low and high resolution imagery meteorological and oceanographic charts TBUS data and operational messages The Internet AUTODIN message DMSP APT and HRPT NOAA and WEFAX Both APT NOAA and WEFAX The WEFAX antenna Ephemeris data allows satellite receiver systems to predict when and where satellites will be at any given moment It also allows receiver systems to earth locate satellites which aids in gridding TBUS data can be obtained via AUTODIN message AWN the fleet multichannel broadcast or via the Internet Part I of the TBUS message contains equator crossing reference information Part IV of the TBUS message contains high precision orbital calculation elements transmission frequencies and remarks The launch year launch number and number of launch pieces About every 2 days Naval Space Surveillance Center Dal
49. CP 11 a logical choice for examining nearby storms VCP 11 provides the most complete coverage of all VCPs and it is normally used when significant echoes are present or severe weather is occurring or anticipated Weather events are more accurately depicted on final products Unfortunately VCP 11 requires a high degree of data processing significantly increasing RPG workload VCP 21 This scans nine elevations in 6 minutes It provides adequate coverage for non severe events continuous rain drizzle Increased data gaps less scans effect performance close to the RDA However adequate coverage is provided for distant storms Mode B clear air mode Clear air does NOT imply cloud free skies but rather the absence of precipitation from radar In other words the criteria for the WSR 88D to use the precipitation mode VCP s 11 and 21 has not been met over the coverage area of the radar Mode B contains VCPs 31 and 32 both complete five elevations in 10 minutes both scan slower than mode A and both contain larger data gaps than VCP 11 or 21 However in precipitation free environments these VCPs are extremely helpful in detecting the early formation of convective precipitation They are also helpful in detecting air mass discontinuities and monitoring precipitation onset VCP 31 This pattern contains the longest pulse 4 7 microseconds and the lowest PRF of all VCPs recall a longer pulse contains more power and incr
50. Define and identify effects of diffraction and ground clutter on radar systems How does pulse volume affect radar power Which beamwidth would provide better target resolution a large beamwidth or a small idth beamwidth Identify effects of scattering absorption and What is the effect of beam broadening on radar solar activity on radar systems pulses As a radar pulse travels through the atmosphere various physical actions cause the energy of the pulse to decrease In this section we will describe these physical actions and their effect on radar systems REFRACTION A common misconception about a radar beam 15 that it travels in a straight line much like that of a laser beam In reality the beam electromagnetic wave 1s actually bent due to differences in atmospheric density These density differences both vertical and horizontal affect the speed and direction of electromagnetic waves In some regions a wave may speed up while in other regions it may slow down When one portion of a wave is slowed and another portion is not the wave bends in the direction of the slower portion of the wave This bending 1s known as refraction Refraction in the atmosphere is ultimately caused by variations in temperature moisture and pressure with changes in moisture having the greatest impact Refractive Index and Refractivity In free space an electromagnetic wave will travel in a straight line because the velocity of the w
51. E SOLAR SPECTRUM NOT TO SC AGM3f110 Figure 1 10 A The electromagnetic spectrum and B the distribution of solar energy incident to the earth Visual Imagery The electromagnetic energy that your eyes can see visible light ranges from a wavelength of 7 um for red light through the visible spectrum red orange yellow green blue indigo and violet to 4 um for violet light view B shows the distribution of the various wavelengths of solar energy incident on the earth s atmosphere About 44 percent of the sun s energy falls on the earth in the form of light Although some light is absorbed much of the light incident on the earth s atmosphere and surface is reflected back into space The reflected light from the earth is measured by a sensor aboard the satellite that is sensitive only to electromagnetic energy in the visual range The sensor measures the energy seen in each pixel and assigns it a reading from 0 for no energy sensed to 256 for very high energy sensed Measurements are transmitted to the earth and the consecutive pixels and scan lines are processed to compose an image 01501 24751 D re The more direct sunlight reaching objects the brighter they will appear The amount of reflectivity of an object is termed albedo and is dependent on the object s surface texture and color In visual range images areas of low reflected light low albedo such as water and forest regions appear blac
52. FAX imagery The operator must update satellite ephemeris data for each polar orbiting satellite at least once every 2 weeks Selected prediction information from Part IV of the TBUS or NASA 2 line bulletins may be manually entered via the keyboard or copied directly from a data disk Orbital prediction information 15 available via message over the Automated Weather Network AWN by standard AUTODIN message or by using a computer modem connection to various sources such as the Internet Complete information on the operation of the IMOSS satellite module including antenna orientation procedures updating ephemeris data gridding and display of satellite imagery is contained in the IMOSS user s guide The manual is provided with each module by the Naval Oceanographic Office REVIEW QUESTIONS Which types of satellite imagery may be acquired by using the AN SMQ 11 039 Q40 Which types of satellite imagery may be acquired by using the IMOSS satellite module 1 30 041 Which satellite antenna of the IMOSS satellite module must be manually oriented towards geostationary satellites EPHEMERIS INFORMATION LEARNING OBJECTIVES Identify the various orbital prediction bulletins and explain how they are obtained Recognize how data from satellite orbital prediction bulletins 1s used to update user operated satellite receivers One of the most critical operations on any of the direct readout satellite imagery receiving s
53. N due to decreasing temperature is not sufficient to offset the decrease in N due to a decrease in moisture and pressure As a result refractivity values will normally decrease with increasing height NOTE It is sometimes advantageous to compute refractivity 1n terms of waves traveling in a straight line This may be approximated by replacing the actual earth s radius curved earth with one approximately four thirds as great flat earth The refractivity using this orientation is called modified refractivity and is expressed in M units Several software programs such as GFMPL automatically compute N units and M units from radiosonde data N units can also be computed from a special Skew T Log P diagram with a refractivity overprint DOD WPC 19 16 2 A refractivity nomogram such as the one in Appendix II can also be used Refractive Conditions Under normal atmospheric conditions when there is a gradual decrease of pressure temperature and humidity with height a radar beam s curvature 1 slightly less than the earth s curvature This causes it to gradually climb higher with distance and 1s called standard or normal refraction view A When there is an unusual or other than normal vertical distributions of moisture and or temperature nonstandard refraction or anomalous propagation AP takes place This causes exaggerated bending of the beam either up or down There are three categories of anomalous propagation subrefraction
54. NONRESIDENT TRAINING COURSE April 1999 Aerographer s Mate Module 3 Environmental Satellites and Weather Radar NAVEDTRA 14271 NOTICE Pages 2 35 2 39 2 41 2 42 2 44 2 45 2 47 2 53 2 54 must be printed on a COLOR printer DISTRIBUTION STATEMENT A Approved for public release distribution is unlimited Although the words he him and his are used sparingly in this course to enhance communication they are not intended to be gender driven or to affront or discriminate against anyone DISTRIBUTION STATEMENT A Approved for public release distribution is unlimited PREFACE By enrolling in this self study course you have demonstrated a desire to improve yourself and the Navy Remember however this self study course is only one part of the total Navy training program Practical experience schools selected reading and your desire to succeed are also necessary to successfully round out a fully meaningful training program THE COURSE This self study course is organized into subject matter areas each containing learning objectives to help you determine what you should learn along with text and illustrations to help you understand the information subject matter reflects day to day requirements and experiences of personnel in the rating or skill area It also reflects guidance provided by Enlisted Community Managers and other senior personnel technical references instructions etc and ei
55. Pa Li E X s WR CM Ow EI vo Ww E a us By iy 2 o a Ev 4 DES 4 1 5 m Wess mt ww pedestal controls antenna movement with pinpoint accuracy It rotates the antenna continuously at a maximum speed of 5 revolutions per minute and automatically changes elevation angles in predetermined increments RADOME A spherical cover that protects the antenna Made of rigid fiberglass the radome measures about 39 ft in diameter and resembles a giant golf ball Its design inhibits ice and snow buildup Figure 2 27 shows the antenna pedestal and radome Figure 2 26 WSR 88D Radar Data Acquisition RDA 2 24 45 ANTENNA 28 PARABOLIC DISH RADOME A SHELL LIKE UNIT WHICH HOUSES AND PROTECTS THE ANTENNA COMPONENTS FROM THE ELEMENTS PEDESTAL SUPPORTS ANTENNA ROTATES CONTINUOUSLY TILTS DISH THROUGH PREPROGRAMMED ELEVATION ANGLES AGM3F227 3 5 2 9 1 5 0 5 SHOWN ARE SOME OF THE ELEVATION ANGLES AVAILABLE TO THE WSR 88D ALL ANTENNA COMPONENTS REST ATOP A 98 TALL TOWER Figure 2 27 WSR 88D antenna pedestal and radome TRANSMITTER The transmitter is amplifier that generates high powered pulses which are then radiated by the antenna By producing nearly triple the power of earlier radars the transmitter 1s t
56. SM I measures thermal energy emitted and reflected by the earth s surface and atmosphere by using the microwave portion of the electromagnetic spectrum SSM I data 1 particularly useful in water vapor and sea ice analysis In addition wind speeds over ocean areas can be estimated by evaluating the brightness temperatures of the white caps of the waves DMSP satellites are launched as F series satellites F 12 F 13 etc A few satellites are equipped with a high frequency radar device known as a scatterometer scatterometer measures reflected microwave signals from ocean waves This data is then used to estimate low level wind speed and direction over data sparse ocean areas Scatterometry data is available from FNMOC FOREIGN SATELLITES Several other countries also support active meteorological satellite programs China operates a geostationary satellite called the Fengyun Russia has Meteor polar orbiting satellites and GOMS geostationary satellites service They also support a Joint project with India that has a geostationary satellite the NSAT place over the Indian Ocean Japan supports a geostationary satellite called the GMS over the western Pacific Ocean In Western Europe several nations jointly support the European Space Agency ESA ESA maintains a geostationary meteorological satellite called METEOSAT in place over the Mediterranean region Figure 1 9 shows the global scale monitoring program of the World
57. Satellite Since that time numerous satellites with more advanced technology have been introduced and today there are many different designs of meteorological and oceanographic satellites Most of these satellites have a variety of sensor packages that survey electromagnetic energy at several different wavelengths 10 MNUTES AFTER ASCENDING NODE LATITUDE 30 N ASCENDING NODE TIME REFERENCE 0 DAY 1 CONDITION PERIGEE IS LOCATED AT THE EQUATOR APOGEE PERIGEE DAY N CONDITION PERIGEE IS NEAR THE SOUTH POLE AGMY3f104 EQUATOR TIME REFERENCE 0 10 MINUTES AFTER ASCENDING NODE LATITUDE 15 Figure 1 4 Typical elliptical satellite orbit and changes the orbital shape over a period of time Besides collecting imagery most environmental satellites perform additional functions Some satellites contain communications packages designed to receive and relay signals between earth stations and other satellites and to collect and relay observation reports from automatic observation sites or buoys Some satellites carry search and rescue SAR beacon locators More advanced satellites carry sophisticated instruments known as atmospheric sounders These systems use infrared and microwave energy to provide vertical temperature and moisture profiles of earth s atmosphere from the surface up to 30 miles They also evaluate atmospheric stability In addition satellites can be used to measure a variety of other envi
58. U ss P Ww T Mi LI L T E BLACK 134 3 89 3 44 3 0 7 67 3 165 3 F 56 8 31 8 6 8 182 552 110 2 C 330 0 305 0 280 0 255 0 218 0 163 TEMPERATURE AGM3f115 Figure 1 15 of a basic enhancement curve table solid line AB represents a case of no enhancement As an example if you acquired an image and the warmer darker end of the spectrum required greater definition the data could be modified as illustrated by the segment AC In this case all the gray shades from 56 0 C to 5 8 C would be displayed Enhancement curves for high resolution imagery from DMSP and NOAA satellites are usually developed based upon three basic configurations depending on desired results They are the single enhancement the high low enhancement and the split enhancement SINGLE ENHANCEMENT The single enhancement curve is defined over a complete count value range but for either a default or specified temperature range This curve will give you all gray shades across your defined temperature range For example if you were interested in only low clouds or sea surface temperatures you might only enhance the image in a range from 20 C to 10 C as shown in Any areas on the image colder than the lower limit will appear white Areas warmer than the upper limit will appear black HIGH LOW ENHANCEMENT For high l
59. UP It also produces interperative products similar to the WSR 88D ARCHIVING Archiving is simply the process of preserving data for long term storage As information passes from one component to another archiving may be accomplished in different formats The WSR 88D uses two types of storage devices an 8mm magnetic tape and a 5 1 4 inch optical laser disc The act of archiving occurs at four locations throughout the system These are identified as Archive Levels I IL IIT and IV Archive Levels I and II are accomplished at the RDA This archived data consists of system maintenance information and digital base data from the signal processor The Archive Level III interface 1 located at the RPG At this level all products produced by the RPG can be saved The Archive Level IV interface is located at each PUP Only data available at the PUP may be recorded at Archive Level IV at the discretion of the user VOLUME COVERAGE PATTERNS Smart scanning strategies are extremely important in optimizing the WSR 88D s detection capability Unlike older units the WSR 88D has several different operating modes that can function automatically and continuously The antenna 15 also capable of scanning rotating at several different elevation angles The WSR 88D has a beamwidth of 1 and thus creates 360 beams or radials of information per elevation angle The area covered by one complete 360 rotation at one elevation angle is called an el
60. a figure 1 25 and is normally installed on a rooftop ashore Some systems are equipped with a multi frequency array antenna ANLSMQ 11C The shipboard version of the AN SMQ 11 contains additional circuits for control and stabilization of the antenna to compensate for ship motions Operation of the ANISMQ 11 is described in detail in NAVAIR 50 30SMQ 11 Organizational Maintenance with Illustrated Parts Breakdown Receiver Recorder Set ELECTRONIC CABINET CY 8839 SMQ 11 1217AS203 1 RECEIVER DEMODULATOR R 2590 SMQ 11 12171 800 1 ANTENNA CONTROL C 1193 5 11 1425AS500 2 TELEVISION MONITOR D TV 4 SMQ 11 3511 300 PROCESSOR COMPUTER CP 2368 SMQ 11 3511AS400 DATA SECURITY EQUIPMENT F KG 44 TSEC OR KG 44A TSEC A Electronic Cabinet CY 8839 SMQ 11 B Receiver Demodulator R 2590 5MQ 11 C Antenna Control C 11933 P SMC 11 D Television Monitor TV 4 5MQ 11 E Processor Computer CP 2368 5MQ 11 Meteorological Data AN SMQ 11 This manual includes operator instructions At most sites the AN SMQ 11 satellite receiver system is cross connected to the Tactical Environmental Support System TESS Imagery received by the AN SMQ 11 may be called into the TESS terminal for processing display and analysis Additionally much of the operation and control of the AN SMQT 11 can be performed through the TESS keyboard The directional antenna of AN SMQ 11 system must be aimed at the satellites to recei
61. ak in returned energy between targets As their energy 15 merged they appear to occupy the entire beam Position C illustrates poor azimuthal resolution and target stretching caused by partial beam filling Range Resolution Range resolution is the radar s ability to display in line targets separately Range resolution affects targets along the beam oriented behind one another Targets must be more than one half pulse length apart or they occupy the pulse together their returned energy 15 merged making it impossible for the radar to see their separation Targets too close together appear as one and are displayed accordingly stretched along the beam axis Range resolution is solely a function of pulse length Pulse length is unaffected by distance therefore separation criteria remains constant In a radar pulse is approaching two objects targets that are one half pulse length apart view In view B the pulse has hit the first target and some of the energy is reflected back to the radar In view C the pulse has just reached the second target and more energy 15 reflected back to the radar from the first target In view D the pulse strikes the second target and energy is now reflected back from that target In view E reflected energy from the first target continues to reflect towards the radar along with the second target which is now one half pulse length long Its front end 15 nearly coincident with the firs
62. also contains default values for the WSR 88D Part B Doppler Radar Theory and Meteorology contains a detailed description of the WSR 88D along with a functional overview of system components It also contains valuable information on the interpretation of Doppler velocity patterns Part C WSR SSD Products and Algorithms describes the various products and algorithms of the WSR 88D and provides information on the different operational modes Part D WSR 8SD Unit Description and Operational Applications provides an in depth description of the various components of the WSR 88D and discusses the operational applications of meteorological and non meteorological echoes The Operator s Handbook Principal User Processor consists of three volumes and 15 the best guide to learning the operation of the PUP workstation Volume I contains information on the graphic tablet and Volume II contains information on the applications terminal Volume III details information on the system console SUMMARY In this chapter we covered the WSR 88D Doppler weather radar system We began with a discussion of electromagnetic energy and radar theory Then we discussed the basic principles of radar propagation and the effects of atmospheric variables on this propagation We then introduced you to Doppler radar theory and discussed the configuration and communications system of the WSR 88D We completed the chapter with an overview of the strengths and limitation
63. and to the south point 3 This means that the wind is either blowing from west to east or east to west at the height corresponding to the edge of the display remember the pseudo 3 D display Since Doppler velocities are negative along the western side of the display and positive along the eastern side the wind must be THIS PAGE MUST BE PRINTED ON A COLOR PRINTER 2 39 blowing from west to east at the height of the display At point 2 the zero line is oriented east to west In this instance inbound velocities are to the south so the wind direction must be 180 near the surface Figure D is an example of the WSR 88D velocity display As you can see areas of red and orange indicate flow away from the radar while areas of green and blue indicate flow toward the radar The colors can then be compared to the color scale above to determine wind speed Again successful coverage from this product depends on the size and amount of scatterers available When ground clutter or anomalous propagation contaminate the radar beam all velocities will be biased toward zero When range folding occurs purple shading might obscure valuable data causing you to miss significant features Keep in mind that all velocities are relative to the RDA not the PUP DERIVED PRODUCTS Derived products are enhanced renditions of base products that provide observers and forecasters with a unique perspective of radar information In the following text
64. are most commonly observed on radar at lower elevation angles WEAK ECHO REGIONS WER A weak echo region is that portion of a storm exhibiting below normal returns WERs are normally found at the storm s core They are formed from the absence of water droplets and hail As intensifying updrafts lift mass to greater heights they create an area that 1s void of scatterers no reflectivity This area of weak echoes appears hollow within the storm Notice the weak echo region forming in the lower portions figure 2 34 view A BOUNDED WEAK ECHO REGION BWER If a WER continues to develop it will eventually become bounded on all sides by much stronger reflectivities This occurs as water droplets and hail exit the column at great heights encircling the updraft core as they fall back toward earth Bounded weak echo regions BWERs generally confirm storm STORM MOTION HOOK SIGNATURE development and imply a transition to severe status fig 2 34 view LINE ECHO WAVE PATTERN LEWP A LEWP is simply a line of convective echoes that has become subjected to uneven acceleration When this occurs some portion of the line is propelled faster than other portions causing the line to bend or arch Because of accelerated movements severe weather 1s a regular feature normally occurring ahead of LEWP at and slightly south of the crest With this mind position 2 figure 2 35 stands at great risk of these fast mov
65. arget s ability to backscatter this energy Stronger targets have higher levels of reflectivity and return more energy Thus stronger targets have higher reflectivity values that is higher dBZ levels For example large raindrops backscatter many times more power than drizzle and will produce reflectivity levels 5 to 10 dBZ higher Because of its characteristics hail tends to have exceptionally high reflectivity values And since the WSR 88D displays information in the form of echo intensity levels a severe thunderstorm with hail will appear much more intense than an area of light rain or drizzle VELOCITY Velocity is used to determine wind speed direction and target motion perhaps the movement of a thunderstorm cell The WSR 88D can detect small areas of convergence divergence and even circulation This has proven valuable in alerting whole communities to the onset of strong surface winds and tornadic activity SPECTRUM WIDTH Spectrum width data is another method of determining atmospheric motion Spectrum width examines the degree of velocity 2 23 variance ofparticles scatterers the atmosphere that results from dispersion and mixing Within a single sample volume of the atmosphere many particles of varying size shape and composition move in different directions speeds Because of their differences each particle moves about independently of the others Within this single sample volume the WSR 88D doe
66. arget toward or away from the radar Although Doppler radar enjoyed widespread use for many years cost made it an impractical tool for weather detection Only recently has expense been offset by the technological breakthroughs of the Doppler meteorological radar WSR 88D This shore based radar has capabilities that far exceed those of older Doppler systems These capabilities include a complementary mix of velocity detection increased power and sensitivity and the integration of high tech computers This automation provides forecasters with a wealth of information The WSR 88D not only can detect target motion and velocity but can also examine internal storm circulations as well as detect atmospheric motions in clear air The WSR 88D excels in detecting severe weather events and more important increases advance warning time In addition the increased sensitivity of the WSR 88D allows various meteorological boundaries to be identified These boundaries include synoptic fronts gust fronts drylines land and sea breeze fronts and thunderstorm outflows DOPPLER SHIFT In 1842 the Austrian physicist Johann Christian Doppler first related motion to frequency changes in light and sound Doppler discovered that the shift in frequency caused by moving sources of sound was directly proportional to the speed of the source He then developed mathematical formulas to describe this effect called the Doppler Shift While not given much thought
67. arth originates from the sun The sun s electromagnetic waves propagate through space and into the earth s atmosphere The sun actually radiates electromagnetic energy at several different wavelengths and frequencies ranging from gamma rays to radio waves Collectively these wavelengths and frequencies make up the electromagnetic spectrum as shown in figure Here on earth radar systems transform electrical energy into electromagnetic energy in the form of radio waves GAMMA RAYS 100 GHz 30 GHz ULTRAVIOLET 10 GHz VISIBLE LIGHT 3 GHz INFRARED 1 GHz RADIO 300 MHz MICROWAVE 100 MHz FREQUENCY UNITS 300 kHz 1 hertz Hz 1 cycle par second 1 kilehertz kHz 1 000 hertz 10 hertz 1 megahertz 1 000000 herz 10 hertz 1 gigahertz BHz 1 000 000 000 hartz 10 hertz hertz mes wavelength in meters speed 1D0 kHz of Sight 3 x 104 meters per second WAVELENGTH UNITS 1famtemgiar fm 1075 metar 1 quadribonth meter lpicematar 1072 meter 1 trillionth moter 1nanemete ai 1079 mater 1 bilkonth meter 30 kHz 1 ameter um 1079 meter 1 mater 1 mileneter 103 mater 1 theusandth meter 1 bilomater 103 meters thousand meters 1msgsmeter 105 meters 1 milion meters Each region of the electromagnetic spectrum can be subdivided into narrower frequency bands as shown in figure 2 2 As you can see electromagnetic waves from radar energy normally fall b
68. ased from commercial telephone companies and are maintained by the telephone companies that own them Routine satellite images are transmitted at 15 minute intervals The imagery is normally displayed on a computer monitor that has control access to the various channels of the GOES TAP system GOES TAP users may be connected to one of several satellite field distribution facilities or be connected to another user When connected to a distribution hub the user may select several different channels of imagery sig nals There are several hubs located at various National Weather Service NWS forecasts offices such San Francisco Miami and Kansas City to name a few If the user 1 not connected directly to a hub but connected to another user this arrangement is appro priately called a slave connection The secondary user has no direct choice of incoming imagery signal and only receives the data on the channel selected by the primary user Several Navy and Marine Corps weather stations are connected as slaves Slaved GOES TAP users must coordinate with the primary user if a different channel of imagery is desired Each channel of GOES TAP is a separate broadcast of imagery One channel for example may contain only alternating visual and infrared GOES satellite images of the full disk hemisphere of the earth Another channel may contain visual and infrared GOES images of only the southeastern United States A third channel may con
69. ated you can freely return to your host system as an APUP This capability 1 a breakthrough for weather briefers as it improves 2 3 aviation safety Before its existence the availability of radar data was extremely limited Radar charts were often old and unrepresentative of current conditions WSR 88D systems have been installed in parts of Alaska and at various sites throughout the Pacific allowing for even more versatility For example you may be stationed stateside and be asked to brief your commanding officer on tropical storm conditions in Guam As non associated user you can examine live radar information for storm movement strength and wind velocity You can also analyze for tornadic activity squall lines and other severe weather signatures all from the safety and comfort of your own weather office thousands of miles from the event This is all made possible through the WSR 88D s advanced communications system Note that any WSR 88D site that is located outside of the conterminous United States CONUS is considered a non network site In addition to the WSR 88D PUP workstations a Supplemental Weather Radar SWR is being installed at selected weather stations overseas that do not have access to information provided by the WSR 88D network The SWR is a commercially developed Doppler radar capable of providing real time radar surveillance It consists of a mini antenna and a desktop workstation similar to a WSR 88D P
70. ave is the same everywhere The ratio of the distance a wave would travel in free space to the distance it actually travels in the earth s atmosphere 15 called the refractive index The refractive index 1s symbolized by n and a typical value at the earths surface would be 1 000300 Thus n would gradually decrease to 1 000000 as you move upward toward the theoretical interface between the atmosphere and free space For example in the time it takes for electromagnetic energy to travel a distance of one wavelength in air at 1000 hPa 15 C temperature and 40 percent relative humidity it could have traveled 1 0003 wavelengths in free space which makes 1 0003 the refractive index The normal value of n for the atmosphere near the earths surface varies between 1 000250 and 1 000400 Since the refractive index produces a somewhat unwieldy number we use a scaled refractive index called refractivity Refractivity is symbolized by N and 1 a function of pressure temperature and vapor pressure moisture A result 1 that atmospheric refractivity near the earth s surface normally varies between 250 and 400 N units the smaller the N value the faster the propagation the larger the N value the slower the propagation Refractivity values become smaller with decreasing pressure and decreasing 2 12 moisture but larger with decreasing temperature AII of these variables usually decrease with increasing altitude However the increase in
71. base Strong wind velocities rotational shear or intense reflectivity values from 2 27 thunderstorms are among the more popular criteria used to trigger alerts The RPG may be located many miles from the RDA but remains critical to the production process Without it NO radar products are available It is important to mention the links that exist between these components Considering the volume of data collected the communications link between the RPG and RDA is crucial Without it the system 1s non functional For this reason the RDA and RPG are connected via a wideband communications link which acts as an information superhighway on which massive volumes of data can flow freely refer to fig 2 25 Like the RDA only a single RPG exists for each WSR 88D system It supports all users who subscribe for products of that system PRINCIPAL USER PROCESSOR PUP Up to this point we ve discussed the RDA which transmits and receives radar energy and the RPG which builds products from that energy Now let s discuss how you will gain access to these products The 15 a sophisticated computer workstation that allows human interface with the WSR 88D fig 2 29 Here the observer or forecaster can display or manipulate products freely and perform such functions as zooming to study tornadic activity or screen roaming to examine other weather features Products can also be time lapsed This allows the PUP operator to
72. bit When a satellite in an equatorial orbit moves from west to east in the same direction that the earth rotates its speed and altitude may be adjusted so that it is always located in a stable orbit over the same position on the equator Satellites in these orbits are called geostationary earth synchronous or geosynchronous since they are stationary relative to their position over the equator Their fixed location provides continuous coverage of the same area over a 24 hour period As shown in figure 1 1 satellites with high orbital angles generally cross over the polar regions and are called polar orbiting satellites These satellites orbit the earth about 14 times a day and provide global coverage every 12 hours A single orbit of a polar orbiting satellite is composed of an ascending node which is the period of time when the satellite is traveling from south toward the north and a descending node which is the period of time when the satellite 1s traveling from north toward the south The position directly under a satellite on the surface of the earth is called the satellite subpoint or nadir while the track of the satellite subpoint along the surface of the earth 1 called the satellite path Now let s consider some additional terms used in satellite orbits and satellite tracking Because the earth rotates each time a polar orbiting satellite crosses the equator its position is further west than its position on the previous o
73. cause an effect similar to range folding False or exaggerated echoes are plotted where no meteorological targets exist Keep in mind that ducting 1 also dependent upon the wavelength of the B Er gt TRANSMITTER TRANSMITTED WAVE ISLAND WAVE HORIZON 216 radar The larger the wavelength the deeper the layer has to be before ducting can occur DIFFRACTION Electromagnetic waves tend to follow along the curved surface of an object Diffraction 1s the process that causes waves traveling in a straight path to bend around an object or obstruction The direction of propagating energy 1s changed so that it spreads into a shadow zone as shown in figure 2 16 view In the earth atmosphere system diffraction occurs where the straight line distance between the transmitter and receiver 15 just tangent to the earth s surface as shown figure 2 16 view B Generally the lower the DETECTED THUNDERSTORM NOT DETECTED THUNDERSTORM DIFFRACTION SHADOW ZONE AGM3F216A NETS CN CN DIFFRACTION SHADOW ZQNE Figure 2 16 A Diffraction of a radar wave front around an obstruction B Radar horizon and diffraction region shadow zone 2 14 frequency longer wavelength the more the electromagnetic wave is diffracted Sidelobes are a direct result of diffraction occurring near the edges of a radar antenna
74. ce and cold cloud tops appear white and warm water and land areas appear dark gray to black in an IR image 1 12 infrared image when surface temperatures and cloud top temperatures are relatively the same Water Vapor Imagery Concentrations of water vapor in the atmosphere absorb essentially all 6 7 um radiation coming from below Thus one of the infrared sensors carried aboard the GOES and the METEOSAT measures radiation at this wavelength When the energy measurements from this type of sensor are composed into an image the result shown in is called a water vapor channel or WV image Areas of high water vapor content high humidity appear in the lighter gray shades while lower humidity areas appear darker The main advantage of the water vapor channel is better definition of the moisture distribution in the upper atmosphere If moisture is present in the upper levels we associate this with upward vertical motion Conversely upper level dryness is a good indication t 00 15 055 81 366 4 0005 1640 FULL DISC IR 1540 FULL DISC IR Figure 1 13 GOES full disk hemisphere infrared water vapor WV channel image top and full disk visual VIS image bottom at the same time The WV image shows a better depiction of the extent of the system than the VIS image of downward vertical motion Water vapor imagery can detect these motions without clouds present Circulation patterns in the upper atmosphere including the je
75. cessful coverage depends on the availability of scatterers Base Velocity VEL Product Doppler radar measures only the radial component of motion directly toward or away from the antenna The Base Velocity product VEL presents the mean radial velocity data While only two dimensional data is received a pseudo 3 D analysis 15 displayed Weather features are extracted in both the horizontal and vertical producing valuable information As with Base Velocity a separate product 1s available for each elevation angle in the current volume coverage pattern VCP The Base Velocity VEL product can be used to examine internal storm motions as well as overall atmospheric flow In the horizontal this includes convergence divergence rotation and wind shifts In the vertical this product helps locate low and mid level jet streams and inversion layers Base Velocity is also useful in locating aviation hazards such as turbulence and low level wind shear LLWS Any 2 38 range folded areas as on base reflectivity are displayed in purple velocity data from this product must be referenced to a zero Doppler velocity line The zero Doppler velocity line depicts points along the radar beam where no Doppler motion 1s being detected Remember from our discussion of velocity that this does not mean that no motion is occurring It simply implies that motion in this region 1 not being detected by the radar Doppler velocities
76. city aliasing is a process that causes a Doppler radar to display untrue velocities because of the motion of the target The Nyquist velocity is the maximum unambiguous velocity that can be detected at any given pulse repetition frequency PRF 29 4 mps 57 knots Velocity aliasing and range folding 2 57 A44 A45 46 47 48 A49 A30 ASI 52 53 54 422 A56 A37 58 A59 A60 A61 A62 A63 A64 A63 A66 Radar Data Acquisition RDA Hail Ground clutter and range folding The Radar Product Generator RPG Base products are near real time displays and are available after each scan Derived products are base products that have been modified or enhanced to produce special results Principal User Processor A graphic tablet and puck Associated Principal Users APUPs Dedicated telephone lines Archive Level IV A volumetric product requires the entire volume of radar coverage all elevation angles to be scanned Mode A VCP 11 Precipitation measurement storm warnings and wind profiling The RPS provides an automated way of managing RPG workload and allows users to identify and access up to 20 routinely required products Alert paired products are transmitted whenever criteria for severe weather is met They are sent in conjunction with an alert message Reflectivity values from scatterers in the radars viewing area Tornadoes V
77. ct sphere it flattens over the poles and bulges near the equator The gravitational pull of the earth sun and moon also plays a role When the satellite comes closest to the earth the satellite 15 said to be at perigee and when it is farthest away from the earth the satellite is said to be apogee When at A DESCENDING OVER NIGHT SIDE OF EARTH DESCENDING NODE EQUATOR CROSSING AT 0230 LMT B LMT 0600 SATELLITE B DESCENDING OVER DAY SIDE OF EARTH DESCENDING NODE EQUATOR CROSSING B AT 0930 LMT SATELLITE A ISA DAY ASECENDING SATELLITE SUN SATELLITE B ASCENDING OVER NIGHT SIDE OF EARTH ASCENDING NODE EQUATOR CROSSING AT ABOUT 2030 LMT 4 LMT 1800 SATELLITE A ASCENDING OVER DAY SIDE OF EARTH ASCENDING NODE EQUATOR CROSSING AT ABOUT 1530 LMT SATELLITE ISA NIGHT ASCENDING SATELLITE AGM31103 Figure 1 3 Day ascending and night ascending polar orbits perigee satellites move faster When at apogee satellites travel slower This change in velocity complicates tracking of polar orbiting satellites For convenience and ease of orbit calculations time 1s referenced to zero when a polar orbiting satellite passes the equator northbound and increases through a complete orbital period illustrates the changes that can occur in the perigee and apogee of a satellite over time Most polar orbiting satellites also have anomalies in their orbits An anomaly in an orbit is any
78. d GOES West POLAR ORBITING SATELLITES Polar orbiting satellites closely parallel the earth s longitude lines They pass over the vicinity of the North and South Poles with each revolution As the earth rotates to the east beneath the satellite each pass monitors an area to the west of the previous pass Since TIROS N SATELLITE EQUIPMENT ARRAY DRIVE SUPPORT DIEN ANS S BAN DETECTOR PROTON AND ELECTRON 2 OMNI THERMAL DETECTOR ANTENNA CONTROL SOLAR Gy NWHEEL SUN SENSOR ARRAY 2 L gt LOUVERS 12 DETECTOR 2 4 LL EARTH INERTIAL ao SENSOR MEASUREMENT J ZL FAL AsseweLv 7 Fae 2 4 P he AGT zs T meee LLP EU OOTY eam 4 PLATFORM LIN 7 FA WSN SUNSHADE NITROGEN 4177 Rl X INSTRUMENT TANS a Ng SS 4 MOUNTING PLATFORM HYDRAZINE TANK 2 VERY HGH Nj BEA REACTION S BAND COMMAND RESOLUTION D ANTENNA 3 ANTENNA RADIOMETER STRUCTURE VHF REAL TIME BOUNDING STRATOSPHERIC BATTERY ANTENNA SE UNIT SOUNDING UNIT MODULES 4 ANTENNA ROCKET UHF DATA HIGH RESOLUTION ENGINE COLLECTION INFRARED ASSEMBLY 4 SYSTEM ANTENNA RADIATION SOUNDER AGM3107 Figure 1 7 Advanced TIROS N satellite 1 6 ORBIT 2 AGM3f108 Figure 1 8 Data coverage on successive orbits of a polar orbiting satellite polar orbiting satellites circle the earth at a much lower altitude about 850 km they have the advantage of photographing clouds directl
79. de the radar s normal range returns during the next pulse s listening time causing confusion As the pulse moves away from the radar volume expands and power density decreases The smaller beam 2 56 21 A22 A23 A 24 A25 A26 A27 A28 A29 A30 A31 A32 A33 34 A33 A36 A37 A36 A39 A40 41 42 43 Beam broadening increases pulse volume resulting in decreased signal strength The presence of sidelobes leads to confusion in interpreting targets because short range non meteorological targets are displayed along with main beam targets An increase in beamwidth or target distance Pulse length The bending of electromagnetic waves Moisture N units normally decrease with height Subrefraction A strong inversion The existence of buildings trees or rough terrain near the radar antenna Backscattering Absorbers are mainly oxygen and water vapor means to measure motion The outstanding capabilities of the WSR SSD include velocity detection increased power and sensitivity and the integration of high tech computers It increases A phase shaft is an observable repositioning of a point on a wave between successive transmissions In degrees By measuring phase shift wavelength and the time interval between pulses As a target moves more perpendicular to a radar the velocity detected becomes less than the true velocity Velo
80. derived from base reflectivity Its simplistic display makes for easy interpretation but also limits the product s usefulness The ET product indicates heights of echoes in hundreds of feet above mean sea level MSL The ET product shows only the highest echoes over a given location and uses different colors to represent heights fig 2 40 Targets returning less than 18 0 dBZ clouds are completely omitted from the display ET provides forecasters with a valuable first look tool It allows them to monitor the highest echo tops throughout the radar viewing area Echo heights paint a very good picture of current weather and make excellent indicators of things to come For this reason is of particular interest to forecasters and aviators For example rapidly increasing echo tops might warn of storm intensification while decreasing tops indicate weakening rapid collapse of echo tops may indicate the onset of downburst conditions at the surface Other products should be used for additional guidance in understanding the cause of such changes The ET algorithm does not tally a column s reflectivity like VIL nor does it depict the strongest returns like CR ET merely depicts the highest echoes observed The ET product can also be deceiving Plotted heights are not actual cloud tops but rather the tops of precipitation The clouds themselves are probably less than 18 0 dBZ and thus extend well beyond the ET heights
81. ding node 3 When an ascending node crosses the equator at a particular relative time the descending node of the same orbit will cross the opposite side of the earth at a LMT about 12 hours opposite the ascending node LMT plus one half the nodal period For example if a satellite has a sun synchronous orbit with a day ascending node then the descending node on the other side of the earth will be a night descending node To simplify the situa tion only the relative time of day of the ascending node is referenced For example an environmental satellite known as a day ascending satellite will always be over the sunlight portion of the earth when SATELLITE A moving north and it will always be over the dark side of the earth when traveling south Night ascending satellites will move northward over the dark side of the earth and southward over the sunlight side of the earth The National Oceanic and Atmospheric Administration NOAA normally maintains at least two operational polar orbiting satellites One 15 sun synchronous morning orbit and the other is in a sun synchronous afternoon orbit Thus each satellite provides two images every 24 hours one day image and one night image producing a total of four images a day over any given area When a satellite achieves orbit around the earth the orbit is rarely a perfect circle Most orbits are actually elliptical and they change over time because the earth 1s not a perfe
82. duct would most likely confirm the phenomena and assist the forecaster in evaluating the circumstances surrounding that event This saves time and provides forecasters with the best product for validating the alert occurrence BASE PRODUCTS Recall that the WSR 88D creates two types of products base and derived Base products provide a broad overview of the meteorological situation and are the next best thing to viewing electromagnetic energy in its raw state They graphically illustrate returned energy as reflectivity velocity or spectrum width data Base Reflectivity REF Product As previously discussed a radar measures the amount of electromagnetic energy returned to the antenna The strength of this energy defines a target s intensity With this in mind it stands to reason that stronger intensities ofprecipitation from severe storms will contrast sharply from that of surrounding precipitation In this respect the WSR 88D truly pays off by transforming backscattered energy into useful colorful and interpretable displays 2 34 The practice of displaying reflectivity values from backscattered energy is nothing new However the process and methods used are becoming more sophisticated The increased accuracy of the WSR 88D along with the addition of color makes older radars obsolete Color coded targets placed on geographical background maps increase the effectiveness of radar interpretation by providing a clear and infor
83. e programs and then describe the various types of environmental satellites and explain their purposes We then discuss some of the most common types of satellite imagery and acquaint you with a few basic imagery enhancement techniques We complete the chapter by taking a brief look at some of the equipment and methods that you will use to acquire and process satellite imagery SATELLITE TERMINOLOGY LEARNING OBJECTIVES Define basic terminology used in relation to satellite orbits and satellite tracking Before you can effectively acquire and use satellite imagery it is important that you become familiar with some basic satellite terminology Environmental satellites orbit the earth at various altitudes Some environmental satellites operate lower than 800 kilometers 500 statute miles while others operate as high as 35 800 kilometers 22 300 statute miles To stay in orbit lower altitude satellites must orbit faster than higher altitude satellites As a result satellites in orbit at 800 kilometers complete an orbit in a little over 100 minutes while satellites in orbit at 35 800 kilometers require 24 hours to complete an orbit The inclination angle of a satellite s orbit is the angle the satellite s path makes as the satellite crosses the equator fig 1 1 This term is usually referred to as the satellite inclination Satellites that have an inclination of 0 degrees circle the earth over the equator in an equatorial or
84. ease sensitivity VCP 31 scans slowly to allow sufficient return of energy from clear air scatterers The greatest drawback to using VCP 31 is its reduced Doppler capability While winds and motions are still observed stronger winds are more likely to aliase when scanning with VCP 31 VCP 32 This pattern uses relatively shorter pulses and a higher PRF than VCP 31 It remains sensitive enough to observe most scatterers while increasing Doppler thresholds in clear air mode Of course the weakest features may be lost In clear air mode the decision to use VCP 31 or 32 long pulse vs short pulse is dictated by the meteorological situation and is not always an easy choice to make For example on windy days where ample scatterers are present clouds moisture etc VCP 32 may be the best choice Its shorter pulse makes it less likely to aliase velocities When the atmosphere contains few scatterers such as on cold dry days longer pulses may be required VCP 31 The radar makes some decisions by itself The WSR 88D is designed to operate continuously in B mode but switches automatically to A mode whenever precipitation 1s detected Precipitation 1s classified as the return of reflectivity values greater than or equal to 18 0 dBZ A return to the Clear Air Mode must be manually selected at the UCP REVIEW QUESTIONS The antenna of the WSR 58D is part of what major system component Q44 Q45 Which hydrometeor would
85. ed energy from 4 8 GHz 8 4 cm raindrops Since raindrops tend to flatten as they fall x 8 12 GHz 42 5 cm the surface area that the radar is able to detect Ky K 18 27 GHz 1 7 1 2 cm increases thus increasing energy return Other K 27 40 GHz 12 075 cm important terms relating to electromagnetic waves you inm 40 300 GHz 75 1 mm 202 need to know wavelength amplitude frequency and power Figure 2 2 The electromagnetic spectrum 2 2 HORIZONTALLY POLARIZED ANTENNA 9 THE OBJECT HORIZONTALLY ELECTRIC LINES MAGNETIC LINES ELECTROMAGNETIC ENERGY INTERSECTS VERTICALLY POLARIZED ANTENNA ELECTROMAGNETIC ENERGY INTERSECTS THE OBJECT VERTICALLY AGM3F203 Figure 2 3 Horizontally and vertically polarized electromagnetic waves Wavelength The distance from wave crest to wave crest or trough to trough along an electromagnetic wave s direction of travel is called wavelength Each measurement equals one complete wave or wave cycle and 1 typically expressed centimeters Each wavelength can also be described in terms of degrees with one wavelength equal to 360 fig 2 4 This concept will become very important later when we discuss Doppler radar As radar energy is emitted into the atmosphere it encounters particles of dust dirt and salts in addition to water vapor and precipitation Collectively these are known as scatterers and they
86. ed out to several days Note that the message date time group 021900 shows that the bulletin is transmitted 3 days before the prediction period covered by the message Table 1 3 Explanation of Important TBUS Bulletin Elements TBUS MESSAGE HEADER ONrNrNrNr D4D4H H m m srsr QrLoLoLoLo 55 LLoLoLoLo N4N4N4N4 4 4111411145454 QaLoLoLoLo AAAAAAAAA BBBBB CCCCCCCCCCCC DDEEFFGGHH JJJJJJJ KKKKKKKK LLLLLLLL MMMMMMMM NNNNNNNN 00000000 00000000 RRRRRRRR SSSSSSSSSS aaa bbb dddddddddd JT EBEEBEBEE hhhhhhhh ttt MMDDSS Prediction start MM Month DD Day Q4 SS U S Satellite number TBUS MESSAGE PART I Code group indicator for first three groups reference orbit Reference orbit equator crossing time UTC D D day hour minute 5 5 second Octan t satellite is entering after crossing equator on reference orbit LoLoLoLo Reference orbit equator crossing longitude in degrees and hundredths of a degree period indicator minutes 55 seconds hundreds grou will not be included 100 min 13 sec will be coded as 0013 Nodal Increment L indicator LoLoLoLo degrees and hundredths of degrees longitude between successive equator crossings Orbit of 4th 8th or 12th orbit after reference orbit Time UTC in hours minutes and seconds of satell
87. ed velocity of a target affected as the target moves more perpendicular to a Doppler radar antenna 40 What is velocity aliasing O41 What is meant by the term Nyquist velocity Q42 What would be the Nyquist velocity of a WSR 88D radar operating with a pulse repetition frequency PRF of 1100 043 The Doppler dilemma is a combination of what two difficulties 2 22 WSR 88D SYSTEM FUNDAMENTALS LEARNING OBJECTIVES Identify the major components of the WSR 88D Identify the purpose of the RDA RPG UCP and PUP Recognize the various WSR 88D system users and their capabilities Distinguish between wideband and narrowband communication links Recognize the basic configuration of the National Weather Radar Network Identify the various data archive levels Identify the major volume coverage patterns of the WSR 88D The following text provides an overview of the WSR 88D system layout communication configuration and data flow The WSR 88D is much more than just a radar it is actually a carefully integrated system of basic radar components sophisticated computer hardware and software and a unique communications network Minimum system configuration includes four major components an RDA Radar Data Acquisition an RPG Radar Product Generator a UCP Unit Control Position and a PUP Principal User Processor While these components might be separated by many miles they remain linked to each other through an intricate
88. electively increasing the PRF at shorter ranges to obtain the desired accuracy of measurements The maximum unambiguous range Rmax 1s the longest range to which a transmitted pulse can travel and return to the radar before the next pulse 1 transmitted other words Rmax 1s the maximum distance radar energy can travel round trip between pulses and still produce reliable information The relationship between the PRF and Rmax determines the unambiguous range of the radar The greater the PRF pulses per second the shorter the maximum unambiguous range Rmax of the radar The maximum unambiguous range of any pulse radar can be computed with the formula Rmax where c equals the speed of light 186 000 miles per second Thus the maximum unambiguous range of a radar with a PRF of 318 would be 292 miles 254 nmi 186 000 2 x 318 292 The factor of 2 the formula RANGE UM 2 D 54 2 ACTUAL TARGET DISPLAYED RANGE 124NM EFFECTIVE RANGE 248 ACTUAL TARGET DISTANCE 372NM Figure 2 8 Radar range folding AGM3F 208 2 7 accounts for the pulse traveling to the target and then back to the radar Range Folding While it s true that only targets within a radar s normal range are detected there are exceptions Occasionally a pulse strikes a target outside of normal range and returns during the next pulse s listening time This poses a complex problem known as range folding Range folding
89. elocities moving toward the radar negative values The RDA Lack of target height information To display an estimate of the atmosphere s liquid water vapor content in the vertical Few scatterers in the atmosphere thus drier air Precipitation 2 58 7 A69 A70 72 A73 A74 A73 The Severe Weather Probability SWP product displays only strong convective cells and assigns percentage values based on each cell s chances of producing severe weather A mesocyclone is an area of strong cyclonic rotation found in supercell thunderstorms Base velocity One hour The Hail Index product provides estimates on the probability of hail the probability of severe hail and the maximum expected hail size To view meteorological targets in the vertical from the side The observer can determine cloud layer height and inversion layer height Depth of turbulent layers wind shear intensity boundaries and frontal slopes Freezing rain 2 59
90. ember to be safety conscious at all times INSTRUCTIONS FOR TAKING THE COURSE ASSIGNMENTS The text pages that you are to study are listed at the beginning of each assignment Study these pages carefully before attempting to answer the questions Pay close attention to tables and illustrations and read the learning objectives The learning objectives state what you should be able to do after studying the material Answering the questions correctly helps you accomplish the objectives SELECTING YOUR ANSWERS Read each question carefully then select the BEST answer You may refer freely to the text The answers must be the result of your own work and decisions You are prohibited from referring to or copying the answers of others and from giving answers to anyone else taking the course SUBMITTING YOUR ASSIGNMENTS To have your assignments graded you must be enrolled in the course with the Nonresident Training Course Administration Branch at the Naval Education and Training Professional Development and Technology Center NETPDTC Following enrollment there are two ways of having your assignments graded 1 use the Internet to submit your assignments as you complete them or 2 send all the assignments at one time by mail to NETPDTC Grading on the Internet Internet grading are Advantages to you may submit your answers as soon as you complete an assignment and e you get your results faster usually by the nex
91. etween 200 MHz and 300 GHz A radar transmitter emits this energy into the atmosphere through an antenna While only a fragment of the energy returns it provides a great deal of information The entire process of energy propagating through space striking objects and returning occurs at the speed of light Targets struck by electromagnetic energy are said to have been radiated and the return signals they produce are called radar echoes 10 MH 3 MHz PROPERTIES OF ELECTROMAGNETIC WAVES 1 MHz An electromagnetic wave consists of two fields an electrical field and a magnetic field which are perpendicular to each other and to the direction of propagation of the wave front fig 2 3 Polarization refers to the orientation of the electrical field component of an electromagnetic wave Polarization can be either linear or circular With linear polarization the electromagnetic waves are either horizontally or vertically polarized relative to the earth s surface fig 2 3 10 kHz T Nominal Naminal Most weather radars including the WSR 88D Saec Dern atn dii ind Satien horizontally polarized There are two major benefits to HF 3 30 100 10 this The first 1s that energy returns from man made m UHF 300 1000 1 0 3 m ground targets that have a greater vertical extent than L 1 2 GHz 30 15 cm horizontal extent like buildings are greatly reduced S 2 4 GHz 15 8 cm The second benefit relates to the return
92. evation scan The area covered by the radar beam as the antenna rotates through several elevation scans 0 through 20 is known as a volume scan The RDA can invoke computer driven instructions known as Volume Coverage Patterns VCPs VCPs determine how thoroughly the atmosphere 15 to be scanned They dictate the number of areas to scan the specific elevation angles to examine and the time allotted for this task The scanning process 15 repeated indefinitely or until a change VCP is made Some products may be displayed after just one elevation scan Thus each slice of the atmosphere is immediately available for examination Other products are not available until all elevation angles have been scanned for that particular VCP These products are called volumetric products because the entire volume of radar coverage must be scanned before they can be produced Two operational modes exist with the WSR 88D mode A precipitation mode and mode B clear air mode Each mode contains two VCPs designed specifically for that type of environment Each VCP possesses certain capabilities as well as limitations Mode A precipitation mode Mode A is used during periods of precipitation and convective activity This mode consists of two short pulse 1 57 microsecond modes VCP 11 and VCP 21 VCP 11 This pattern scans 14 elevations in 5 minutes It contains fewer data gaps than other VCPs This increases radar accuracy making V
93. frared satellite imagery The NOAA satellites transmit a pair of images one visual and one infrared over sunlight portions of the earth and two different infrared channels over the dark side of the earth The scan rate is 120 lines per minute at 4 kilometer resolution The amount of data received by a station depends on the location of the satellite subpoint the further the subpoint falls from the station the smaller the area of coverage becomes The received APT images are ungridded no latitude longitude lines nor land wate eographical boundaries are added to the image fig 1 21 APT service 1s also available from foreign polar orbiting 24113385 Woy po1eajui pus Jensia dy 18244 C 94n314 1 23 satellites and varies from relatively low resolution to high resolution APT direct readout imagery is normally transmitted in the 136 MHz to 139 MHz band The data signals are transmitted from the satellite to earth within seconds of being scanned by the satellite sensors This is sometimes called real time imagery the image is available as the satellite scans the earth APT service is designed to be received by anyone with a standard relatively low cost satellite receiver Signals from DMSP satellites also provide APT However the signals are encrypted Additional information on APT direct readout services may be found in the NOAA KLM User s Guide The IMOSS satellite module can rece
94. gy is permanently lost to the radar Not all forms of scattering are attenuation Backscattering for example occurs when energy is reflected back toward the antenna resulting in a net gain Larger targets tend to backscatter significantly more energy than smaller ones do and therefore result in stronger returns Without backscattering no targets would be detected and no echoes would be plotted The bottom line is that scattering may or may not be attenuation The type and amount of scattering present determines radar performance The degree of scattering 1s not only dependent on particle size and composition but also wavelength Wavelengths used in weather radar are selected to minimize scattering by particles smaller than the radar was designed to detect 1 e clouds and precipitation Figure 2 17 Scattering of radar energy 2 15 Absorption The atmosphere absorbs some amount of EM energy mainly by oxygen and water vapor It becomes trapped within these parcels long enough to become unrecognizable to the radar Absorption like any form of attenuation results in lost power and decreased radar performance Like scattering the degree of absorption 1s dependent on particle size particle composition and wavelength The longer the wavelength the smaller the attenuation due to absorption Solar Effects Due to the high sensitivity of the WSR 88D anomalous returns near sunrise or sunset may occur These false returns a
95. h a discussion of the advantages and limitations of WSR 88D products and the publications associated with the system ELECTROMAGNETIC ENERGY LEARNING OBJECTIVES Describe the properties of electromagnetic energy Define electromagnetic wave electromagnetic spectrum wavelength amplitude frequency and Rower Understanding the fundamentals of electromagnetic EM energy will enhance your ability to use weather radar No matter how sophisticated the radar system theoretical limitations always exist This background knowledge will also help you to understand the operation of the WSR 88D and to effectively use the products it produces In the following text we will begin with a general discussion of electromagnetic energy followed by a description of several properties related to electromagnetic waves ELECTROMAGNETIC WAVES As discussed in chapter 1 of this module all things whose temperature is above absolute zero emit radiation Radiation is energy that travels in the form of waves If this energy were visible it would appear as sine waves with a series of troughs and crests 2 1 Because radiation waves have electrical and Figure 2 1 Electromagnetic energy as sine waves 2 ELECTROMAGNETIC Frequency Frequency FREQUENCY Wavelength SPECTRUM hertz hertz BANOS 30 fm 10 magnetic properties they are called electromagnetic waves Frequency 300 GHz Most of the electromagnetic energy on the e
96. he driving force behind the WSR 88D sensitivity The transmitter has an operating frequency range of 2 700 to 3 000 MHz 2 7 to 3 0 GHz RECEIVER Backscattered energy generally travels many miles before returning at a fraction of its original strength This makes it difficult to interpret Much like a stethoscope helps a doctor hear sounds from deep within your chest the receiver boosts signal strength of backscattered energy to levels at which the radar can extract crucial target information Amplified energy is then routed to the signal processor SIGNAL PROCESSOR The signal processor is the first of four computers within the WSR 88D to encounter radar data Here data coming from the receiver is digitized and contaminants such as range folding and ground clutter are reduced or eliminated This preprocessing converts raw analog data into a digitized base data format 2 25 RDA Special Processes The significance of range folding and ground clutter were discussed earlier in this chapter Two special features of the RDA signal processor include a range unfolding process and a ground clutter filtering process RANGE UNFOLDING The process of cleaning up range folded data must begin by comparing each echo to previous scans If continuity exists for an echo the target is considered real and the test 1s terminated However an echo has mysteriously appeared with no prior history a secondary test 15 performed In such
97. hese functions control hardware and software throughout the entire system Application Terminal The applications terminal manipulates or changes hardware performance It controls RDA and RPG operations including product generation distribution and storage It manages internal communications and allows the isolation of individual components or the disconnection of any user It controls all message traffic between individual users and the UCP operator 2H i and may restrict system access The UCP operator can monitor system status to ensure smooth operation System Console Terminal This function primarily affects software performance It provides user interface to the RPG Specific operations include start up and shutdown of application software executing system diagnostics and performing maintenance operations The UCP normally consists of two monochrome monitors and two keyboards one for each function Some UCPs however use only a single monitor keyboard combination that toggles back and fourth between application and system control functions SYSTEM USERS The WSR 88D is uniquely supported by a triagency program that includes the Department of 230 Figure 2 30 WSR 88D Unit Control Position UCP 2 29 Commerce National Weather Service the Department of Defense Navy Marine Corps Air Force and the Department of Transportation Federal Aviation Administration Day to day product i
98. hgren Virginia 1 39 CHAPTER 2 WEATHER RADAR INTRODUCTION Since the late 1940 s radar has been used to track weather systems Subsequent advances were made in radar transmitters receivers and other system components However with the exception of transistor technology few changes were made to basic weather radar systems through the 1970 s In the late 1970 s work began on the next generation of weather radar NEXRAD using Doppler technology The use of Doppler technology enabled weather radar systems to not only detect meteorological targets with greater detail but also measure target motion and velocity By the mid 1980 s a new weather radar that used this technology was introduced This system 1 known as the weather surveillance radar 1988 Doppler or WSR 88D WSR 88D systems have been installed at several Navy and Marine Corps shore based weather stations Even if you do not have a WSR 88D at your command almost all weather radar information you will receive is derived from Doppler radar Thus it is important that you understand basic Doppler theory and the WSR 88D system In this chapter we discuss the Doppler weather radar WSR 88D We begin with a general explana tion of electromagnetic energy and radar propagation theory followed by a discussion of Doppler radar principles We will then concentrate on the configuration and operation of the WSR 88D system AGM3F201 Finally we complete the chapter wit
99. his limitation poses serious problems since echo heights relate closely to storm development Without height data targets become deceiving This product is normally accompanied by an attribute table that ranks storms according to severity and includes forecast movement and the likelihood of each storm to produce a variety of conditions hail mesocyclones tornadoes etc Keep in mind that values displayed for a given location could have come from any altitude or elevation angle In fact extensive ground clutter may severely contaminate this product creating the illusion of intense storms where nothing exists This Occurrence is common when superrefractive conditions are present Figure 2 37 is an example of the Composite Reflectivity product Vertically Integrated Liquid VIL Product Most WSR 88D products emphasize a target s horizontal details The Vertically Integrated Liquid VIL product provides an estimate of atmospheric liquid water content in the vertical It serves a multitude of purposes but 15 primarily designed to evaluate storm severity The VIL product is compiled from extensive reanalysis of base reflectivity data It totals reflectivity within a given column of the atmosphere and then displays a product of tallied values The function of the VIL algorithm is to estimate the amount of liquid water contained in a storm and then display that value kilograms meter squared in a graphical form In its initial stages
100. icyclonic rotation Figure 2 47 fs an example of the Velocity Cross Section product The limitations of this product are similar to the Reflectivity Cross Section product Keep in mind that the plane along which the cross section is built MUST be either parallel or perpendicular to the radar viewing direction If the cross section is cut at any other angle you are viewing the radial component of radial velocities This makes the data extremely hard to interpret RADAR CODED MESSAGES The Radar Coded Message is a high resolution product that provides summary radar information It 1s primarily used in the preparation of the National Radar Summary Chart The message is composed of three parts Part A is a reflectivity graphic product that 1s automatically generated by the system The local grid at each antenna site is designed to become part of the national radar grid Part B contains a single profile of the horizontal wind information derived from the output of the Velocity Azimuth Display VAD algorithm It is also produced automatically and 1s presented to the user as an alphanumeric message Part C contains remarks in an alphanumeric format Remarks such as tornadic vortex signatures SPZJEWOV Figure 2 45 Hail Index HI product 2 52 09723790 28 5 HAIL INDEX 59 124 05 25 98 08 55 35719758N 1227 92716 4 MODE 21 CNTE anEG ONM AYR CRDA QUEUE 1
101. ing storms The speed of the LEWP itself is a good indicator of its severity STRONG REFLECTIVITY GRADIENTS From a radar perspective monitoring rapid changes can best be accomplished by monitoring reflectivity gradients transition zones For instance if the temperature in Chicago is 55 F and the temperature in Biloxi is 65 F the thermal gradient between these two cities is weak However if this same amount of change occurred between New Orleans and Biloxi the gradient would be much stronger For radar purposes reflectivity gradients illustrate the sharpness or contrast between a storm and its surroundings The sharper the gradient the greater potential for severe weather Enhanced resolution color and digitized displays make reflectivity gradients more observable than ever REFLECTIVITY 7 VALUES AGM3F233 Figure 2 33 Thunderstorm cell exhibiting a classic hook signature A B n e oe Figure 2 34 Thunderstorm cell exhibiting A Weak Echo Region WER B Bounded Weak Echo Region BWER We tend to place a great deal of emphasis on severe weather detection However reflectivity serves many other practical uses on a daily basis For example we know that precipitation produces a minimum of 18 0 dBZ reflectivity return Therefore returns of less than 18 0 dBZ might be attributed to nonprecipitable cloud droplets or other minute scatterers From this we can estima
102. ins a built in satellite receiver and processor It also includes a VHF receiver demodulator and two antennas One antenna is an omnidirectional antenna used to copy APT signals and the other is used to copy signals from the WEFAX broadcast The SAT MOD is equipped with special software modifications that can be used independently from the main IMOSS 1 29 computer Satellite imagery received via the satellite module may be transferred to the main IMOSS computer by using a 1 44MB data disk All com ponents are equipped with protective cases fig 1 26 Because the APT antenna 1s omnidirectional no antenna aiming is required to track polar orbiting satellites or geostationary satellites When the system is powered up the receiver will automatically scan satellite frequencies detect imagery signals and acquire the imagery The WEFAX antenna must be manually oriented toward the geostationary satellite during initial setup of the system For planning the system contains software that displays orbital predictions and line of sight receiver ranges for the polar orbiting APT and geostationary satellite WEFAX transmissions Menu options on the liquid crystal display LCD screen guide the operator LAPTOP COMPUTER APT ANTENNA WEFAX ANTENNA AGM3f126 Figure 1 26 Interim Mobile Oceanography Support System IMOSS satellite module through processing gridding and enhancement options for various APT direct readout and WE
103. irect its movement A radar beam is the path that guides a pulse s travel Energy emitted into the atmosphere remains concentrated along the beam axis As you move outward at right angles to this axis power density gradually decreases At some point power density equals one half of that found at the beam axis These half power points wrap completely around the beam and define its shape in terms of height and width or more appropriately its circumference The area within these half power points is defined as the beam and it contains nearly 80 percent of all energy 2 10 The angular distance between half powerpoints in a plane passing through the beam centerline is the 2 8 beamwidth Beamwidth varies directly with wavelength and inversely with antenna size Radar systems that produce relatively small beam widths generally provide greater target resolution Beam Broadening As pulses travel away from the antenna the beam takes on a cone like appearance and expands in all directions This expansion or beam broadening increases pulse volume resulting in decreased signal strength fig 2 11 Distant targets appear distorted in fact they may not be seen at all Beam broadening also causes partial beam filling which implies that distant targets occupy proportionally less of an expanded beam Thus the true characteristics of a target may be hidden or altered during display Beam broadening reduces azimuthal resolution and prod
104. ite equator crossing 4h 8th or 12th orbit after reference orbit Octant satellite is entering after crossing equator on 4th 8th or 12th orbit after reference orbit LoLoLoLo Equator crossing longitude after reference orbit TBUS MESSAGE PART IV International satellite identification Hou n Ww Ww i Orbit number at epoch Time of the first ascending node in days from the beginning of the year 9 decimal places Epoch calendar date time DD Year EE month FF day GG hour HH minutes and seconds 3 decimal places Apparent Greenwich Hour Angle at epoch 4 decimal places Mean period of anomaly min 4 decimal places Nodal period min 4 decimal places Eccentricity 8 decimal places Argument of perigee deg 5 decimal places Right Ascension of ascending node deg 5 decimal places Inclination deg 5 decimal places Mean anomaly deg 5 decimal places Semi major axis of orbit km 3 decimal places Epoch X position component km 4 decimal places Epoch Y position component km 4 decimal places Epoch Z position component km 4 decimal places Epoch X velocity component km sec 6 decimal places Epoch Y velocity component km sec 6 decimal places Epoch Z velocity component km sec 6 decimal places Ballistics coefficient CD A M m kg to eight decimal places Daily solar flux value 10 7 cm 10 Wim 90 day running mean of solar flux 10 7 W m Planetary
105. ite receivers The service is generally provided at frequencies near 1691 MHz 1 25 The WEFAX signal is much weaker than the APT HRPT signal from polar orbiting satellites Normally a directional antenna with antenna polarity control circuits is necessary to copy the WEFAX signal The AN SMQ 11 is fully capable of capturing the WEFAX signal The IMOSS satellite module can also receive and process the WEFAX signal by using a special directional antenna specifically designed to copy the broadcast Directional antennas should be aimed at the broadcasting geostationary satellite for the best WEFAX reception Instructions for aiming the IMOSS WEFAX antenna are available in the Interim Mobile Oceanography Support System IMOSS User s Guide Appendix C of the guide contains diagrams for calculating elevation and azimuth angles for different geostationary satellites Be aware that although international agreements call for five operational geostationary satellites problems occasionally arise that require satellites to be moved temporarily to slightly different locations WEFAX may also be broadcast from older geostationary satellites that have been moved out of the primary position is a diagram frequently used to calculate the azimuth degrees true and elevation angles needed to find any geostationary satellite located over the equator To use the diagram the user subtracts the longitude of the receiver location site longitude fro
106. ive process display grid and enhance APT direct readout service from nearly all polar orbiting environmental satellites It is not equipped to decrypt the imagery signal from the DMSP satellites The AN SMQ 11 is capable of copying both APT data as well as DMSP encrypted signals A second type of direct readout service available from both the NOAA and DMSP satellites is the High Resolution Picture Transmission HRPT service This is data scanned at a rate of 360 lines per minute to provide 1 1 kilometer resolution fig 1 22 High resolution imagery can be and usually is transmitted from satellites as a continuous broadcast HRPT 19 41 01 1796 1 NHRPT VIS Figure 1 22 HRPT imagery 1 24 imagery like the APT direct broadcast imagery is received unprocessed and ungridded Many user operated satellite receiver systems are unable to receive and process I IRPT imagery The IMOSS satellite module cannot receive or process HRPT while the AN SMQ 11 is able to receive and process the signal High resolution 1magery may also be stored aboard the satellite downloaded to a Command Data Acquisition CDA station on command and sent to NESDIS Suitland Maryland NESDIS processes the imagery adds gridding and forwards the processed signal to other imagery services NESDIS operates two CDA stations for both the NOAA and GOES satellites Wallops Island Virginia and Fairbanks Alaska Department of Defense operates its o
107. k Areas of high reflected light high albedo such as snow appear white fig 1 11 Cloud tops reflect a lot of light so they are usually very light shades Space surrounding earth reflects no light so it appears black Visible imagery is very useful in both atmospheric and oceanographic analysis because reflectivity varies considerably among atmospheric land and oceanic features An obvious disadvantage of visible imagery is that it is only available during daylight hours Infrared Imagery Look again at figure 1 10 view B You can see that most of the sun s energy that falls on the earth is in the infrared band Most of the shorter wavelengths of infrared energy are reflected from the earth much the i 7 i uM Figure 1 11 GOES visual VIS image Space and low reflective areas appear black while high reflective areas such as cloud tops appear white 1 11 same as visible light longer wavelength infrared energy is absorbed Satellites normally carry sensors that measure energy levels in several specific bands of infrared wavelengths and the radiation measured 1s directly related to the temperature of the different radiating surfaces Since all surfaces radiate some amount of thermal heat energy a major advantage of infrared satellite imagery is that it is available even when the earth is dark Energy levels are measured much the same way that visual range energy is measured The individual measureme
108. l potential then categorized accordingly While the algorithm 1 not foolproof it provides a valuable first guess The hail product provides estimates on the probability of hail probability of severe hail and maximum expected hail size The hail product provides an extremely simple display making it a good overlay for other products As you can see in figure vPPCJEWOV Figure 2 44 Storm Track Information STI product 2 50 SH Be STORM TRACK 58 STI 248 NM 95 25 98 08 55 ROA ETL 23941375H 1277 avsclez4uH NODE 21 22H0EG 24 IDENTIFIED STM MaG 45 BOR QUELIE 23 2045 ARCHIVE UNIT 1 READ DONE HAROCOFY SELECTEL 2 45 leach storm is assigned a unique alphanumeric identifier The small green triangles that are not filled in indicate the probability of hail of any size within that particular storm The small green filled triangles indicate the probability of hail equal to or greater than 3 4 of an inch The numbers inside the larger green triangles indicate maximum expected hail size to the nearest whole inch In any case the Hail Index product quickly indicates the possibility of severe weather in the radar coverage area Hail is a volumetric product therefore it 1 only available at the end of a volume scan It requires input from several sources and contamination at any level results in a loss of the product While the hail product 15
109. l software programs are in use in various systems to automatically calculate polar orbiting satellite orbits and antenna aiming data The AN SMQ 11 system and the SAT MOD both perform these functions but rather differently TESS which may be used to control the AN SMQ 11 also has a separate orbital prediction function Software upgrades are in development that will alleviate some of these differences In this section we will discuss how to interpret various elements of ephemeris information from the most common polar orbiting satellite prediction bulletins The exact information required as well as data entry methods for each system are discussed in the individual operator s manuals Ephemeris data for each polar orbiting satellite 1s available from several sources Information for the NOAA satellites is available from the National Weather Service telecommunications center as NOAA APT Predict bulletins and from NASA as Two Line Orbital Elements bulletins Orbital information for the DMSP satellites all foreign operated polar orbiting satellites 15 available from the Naval Space Surveillance Center Dahlgren Virginia as C Element Orbital Data and Satellite Equator Crossings bulletins NOAA APT PREDICT BULLETINS TBUS NOAA APT Predict bulletins because of the message s data identifier TBUS are more commonly referred to as TBUS data These bulletins are routinely provided over the WEFAX broadcast and the automated weathe
110. lable to strike targets both signal strength and data reliability are increased and the radar performs more efficiently Electromagnetic waves can be described in terms of either frequency or wavelength Looking back at you can see the function of frequency versus wavelength Power Power 1s the rate at which energy is used With electromagnetic energy the decibel system 15 used to compare two power values A decibel abbreviated dB 1s one tenth of a bel the fundamental unit The decibel system 15 useful for comparing power values 1 AMPLITUDE that differ greatly such as transmitter and receiver power Values for dB are measured logarithmically not linearly With this in mind you must be aware that every change of 3 dB corresponds to a doubling or halving of power Doppler reflectivity values which will be discussed later are indicated by the abbreviation dBZ REVIEW QUESTIONS Q1 What is an electromagnetic wave Q2 Radar energy occupies what portion of the electromagnetic spectrum Q3 Wavelength is usually measured in what units Q4 How does wavelength affect a radar s ability to detect different types of targets Qs Define radar frequency 06 Given a frequency of 200 MHz and a frequency of 100 GHz which one has a shorter wavelength Q7 How can different radar power values be compared BASIC RADAR CONFIGURATION LEARNING OBJECTIVES Define reflectivity Identify the major parts of a radar s
111. like to communicate with us regarding this course we encourage you if possible to use e mail If you write or fax please use a copy of the Student Comment form that follows this page vii For subject matter questions E mail Phone n315 products cnet navy mil Comm 850 452 1001 Ext 1713 DSN 922 1001 Ext 1713 FAX 850 452 1370 Do not fax answer sheets COMMANDING OFFICER NETPDTC CODE N315 6490 SAUFLEY FIELD ROAD PENSACOLA FL 32509 5000 Address For enrollment shipping completion letter questions grading or E mail Phone fleetservices cnet navy mil Toll Free 877 264 8583 Comm 850 452 1511 1181 1859 DSN 922 1511 1181 1859 FAX 850 452 1370 Do not fax answer sheets COMMANDING OFFICER NETPDTC CODE N331 6490 SAUFLEY FIELD ROAD PENSACOLA FL 32559 5000 Address NAVAL RESERVE RETIREMENT CREDIT If you are a member of the Naval Reserve you will receive retirement points if you are authorized to receive them under current directives governing retirement of Naval Reserve personnel For Naval Reserve retirement this course is evaluated at 2 points Refer to Administrative Procedures for Naval Reservists on Inactive Duty BUPERSINST 1001 39 for more information about retirement points COURSE OBJECTIVES In completing this nonresident training course you will demonstrate a knowledge of the subject matter by correctly answering questions on the following subjects
112. llites therefore the satellite can only see a limited portion of the earth as the satellite sensors scan from horizon to horizon Because of the acute view angle near the horizon the satellite image near the horizon is usually of little value and 1 usually not processed or displayed by receiver station equipment IMAGERY RESOLUTION Satellite sensors designed to produce pictures or images of earth its oceans and its atmosphere are very different from the cameras used to take a photograph They are more like a video camera only much more specialized These scanning sensors are called radiometers and instead of film an electronic circuit sensitive only to a small range of electromagnetic wavelengths measures the amount of energy that is received Satellites may can y several different image sensors each of which is sensitive to only a small band of energy at a specific wavelength The radiometer used by the TIROS N and POES series satellites 1s known as the Advanced Very High Resolution Radiometer AVHRR and contains many types of sensors Satellite sensors scan across the surface of the earth in consecutive scan lines along a path normal to the direction of travel of the satellite As the sensor moves through a scan line it very rapidly measures energy levels for only a very small portion of the earth at a time Each individual energy measurement will compose a single picture element or pixel of the overall satellite image The se
113. lows the user to see specific details of an image with better definition Infrared imagery is often enhanced to better define a small range of critical temperatures TYPES OF ENHANCEMENT CURVES Unenhanced imagery displays a linear transition of gray shades from black warm to white cold It 1s a steady increase in brightness that produces little contrast Enhanced imagery displays a transition of mostly non linear gray shades The result is an improved contrast of various key temperatures that makes specific temperature assessment much easier There are two methods of enhancing satellite imagery brilliance inversions and thresholding curves Brilliance inversion enhancements use a range of gray shades or color to identify a range of specific temperatures With threshold enhancements a single gray shade is used to identify a whole range of temperatures In other words all the temperatures in a particular range have the same gray contour Figure shows enhanced infrared images User Defined Enhancement Curves When possible enhancement curves should be locally developed and evaluated Most satellite receiving equipment used by the Navy such as the AN SMQ 11 allow for the creation of custom designed enhancement curves Keep in mind that when you are developing enhancement curves you should limit the number of features to be enhanced You must allow for enough detail as possible without making the display too confusing There a
114. m the longitude of the satellite to find delta A 1gnore the sign Using the value of A scale on the left side of the diagram with 80 degrees at the bottom and 3 degrees at the top follow parallel to the drawn lines sloping downward toward the right Using the receiver station latitude site latitude on the scale right side of the diagram follow parallel to the lines sloping downward toward the left to the intersection of the A value The antenna elevation angle look elevation 1s found by drawing a horizontal line toward the left to the ook elevation scale The antenna azimuth is found by drawing a vertical line downward to the ook azimuth scale The four azimuth scales are used as follows e SW When receiver is south of the equator and west of the satellite s position SE When the receiver 1 south of the equator and east of the satellite s position NE When the receiver is north of the equator and east of the satellite s position NW 90 100 120 30 140 150 160 170 180 270 260 250 240 230 220 210 200 190 180 270 280 290 300 310 520 330 340 350 360 LOOK AZIMUTH SATELLITE LONGITUDE SITE LONGITUDE SITE LATITUDE AGM3f12 G imi m e NW When the receiver is north of the equator In the example shown on the diagram azimuth and and west of the satellite s position elevation angles are determined for the 75 W GOES from a receiver site at 103 4 W longitude 23 0 N latitude The A
115. magnetic index 2x10 gauss Drag modulation coefficient to four decimal places Radiation pressure coefficient m kg to ten decimal places Perigee motion deg day 5 decimal places Right Ascension of the Ascending Node motion deg day 5 decimal places Rate of change of mean anomaly at epoch deg day 2 decimal places Equator crossing longitude of the epoch reference orbit measure as East longitude 5 decimal places Month date and year MMDDY Y of last TIP clock correction Clock error after last correction measured in seconds to three decimal places Month date and year MMDDY Y of current clock error Current clock error measured in seconds three decimal places signed values P for positive M for negative Month date and year MMDDYY of the measured clock error rate Clock error rate expressed as milliseconds day Month date and year MMDDY Y of next TIP clock correction 000000 if unknown 33 In the TBUS bulletin Part IV all information necessary to calculate a satellite s orbit and variations in the orbit is provided This information includes an epoch orbit number two forms of an epoch date position and velocity coordinates the nodal period and anomaly values used to determine the change in position of the satellite over any period of time SAT MOD Ephemeris Updates Like the TESS the SAT MOD may update ephemeris information by reading a TBUS message file If the appropriate TBUS b
116. mative visual presentation Operators can quickly compare target strengths and distinguish severe cells at a glance Figure 2 32 is an example of the Base Reflectivity REF product Reflectivity data levels are indicated by the color scales found along the product s right margin With base reflectivity the data levels refer to target reflectivity intensity dBZ Rainfall rates can easily be estimated from REF Reflectivities from light rain average around 20 to 25 dBZ while reflectivities from thunderstorms average around 45 to 55 dBZ Normally it 1s difficult to distinguish precipitation type based on reflectivity alone For example snow and light drizzle both produce nearly the same reflectivity values Very high reflectivity values are usually associated with hail Although base reflectivity has a maximum range of 248 nmi its best resolution 54 nmi grid size is limited to 124 nmi from the range folded areas are displayed as purple shading Base reflectivity provides a weather snapshot of the entire radar coverage area Highly reflective storm cores and embedded thunderstorms appear quite nicely in color These same features were difficult to observe on conventional radarscopes Using base reflectivity an operator can also identify distinct radar signatures and correlate targets to their geographical location Radar signatures are visible patterns commonly associated with certain phenomena Meteorologists have
117. may cause operators to base crucial decisions on false echoes The data received from this stray pulse could be misanalyzed and echoes may be plotted where nothing exists The data may look reliable and the radar may appear to be functioning properly adding to the deception of normal operation Refer tol figure 2 8 Assume a pulse was emitted during the radar s previous scan While it travels beyond normal range and strikes a target the radar emits a second pulse Since no targets exist within normal radar range these pulses will pass each other in flight The first pulse now returns while the radar is expecting the second pulse during the listening time of the second pulse The radar believes that the second pulse has struck a target 124 nmi from the antenna and displays an echo accordingly target X The operator is fooled by target X and issues a severe weather warning when in fact no clouds are present Target X was an illusion a reflection of a thunderstorm located 372 nmi from the antenna Fortunately the WSR 88D is equipped with a range unfolding mechanism that attempts to position all echoes properly Pulse Volume As pulses travel they look like a cone with its point cut off fig 2 9 They expand with the beam and increase in volume The volume of a pulse is the space 209 Figure 2 9 Radar pulse volume Pulse volume increases with distance from the antenna as the pulse expands in all
118. mely weak reflectivities light drizzle ice 2 18 crystals etc This sensitivity allows the radar to determine the wind speed from the size of the phase shift Even dust or insects can act as scatterers and enable the WSR 88D to determine wind speeds in clear air The WSR 88D will not always detect every motion in the atmosphere nor will it display them with little or no confusion Since only pulsed energy that returns directly to the antenna can be detected it stands to reason that phase shifts are only observable when they occur directly along the radar beam radial RECEIVER SCATTERED PULSE T1 FIRST PULSE DISTANCE Y N SCATTERED PULSE SECOND PULSE DISTANCE Y 2 220 Figure 2 20 Radial velocity ZERO KTS DETECTED 20 KTS ACTUAL Figure 2 21 Affects of return component on radial velocity Thus Doppler radars can only measure the component of a target s motion that occurs along the radial axis This component is called the radial velocity Motion Parallel Along Radial Axis If a parcel moves directly toward or away from the antenna we say its motion is parallel to the radial axis beam Truly parallel motions allow the phase shift of each wave to become fully visible to the radar The result is that displayed velocities reflect the parcel s true speed In figure 2 21 component the wind is blowing from the west at 20 knots and the antenna 15 pointing toward
119. nally designed to transmit graphical data fields for portable computer systems selected satellite imagery is now available within a few hours of sensing Authorized users may access the system from anywhere in the world via computer modem through the U S Govemment owned Internet routing networks or via direct long distance telephone connection on commercial or Defense Switched Network DSN lines Information on NODDS satellite imagery is available in the Navy Oceanographic Data Distribution System Products Manual All of the satellite data available on NODDS 1 from DMSP satellites The pictures that actually appear on your computer monitor may not be quite as clear as imagery from other sources The imagery is considered near real time in that it is available to the user usually within a few hours of sensing The DMSP satellites collect imagery store the information as digital data aboard the satellite and then dump the imagery data on command as it comes within range of a receiver site capable of copying high resolution imagery DMSP imagery for specific high interest areas around the world may be requested from FNMOC after some coordination GOES TELECOMMUNICATIONS ACCESS PROGRAM GOES TAP Ashore Navy and Marine Corps weather stations receive satellite imagery primarily from the GOES TAP service The GOES TAP service is operated by NESDIS and satellite images are provided via dedicated telephone circuits The circuits are le
120. ndicated in column 6 of the GOES legend 028 029 The GOES temperature scale is normally divided into segments of how many degrees METHODS OF ACQUIRING IMAGERY LEARNING OBJECTIVE Identify the various methods used to acquire environmental satellite imagery There are several ways to receive satellite imagery weather facsimile broadcast Navy Ocean ographic Data Distribution System NODDS GOES Telecommunications Access Program GOES TAP satellite direct readout service weather facsimile ser vice WEFAX the Internet and AUTODIN message WEATHER FACSIMILE BROADCAST Some ships may receive a low quality satellite image as part of the U S Coast Guard facsimile broadcast Transmitted via high frequency HF radio this broadcast transmits National Weather Service 1 21 charts and satellite imagery on fixed schedule Schedules and frequencies for facsimile broadcasts originating from CONUS stations San Francisco New Orleans Boston and Kodiak are available over the Internet Several other countries such as Japan and India also transmit weather charts and satellite imagery via A listing of all maritime weather broadcast frequencies 15 available in the latest edition of Worldwide Marine Radiofacsimile Broadcast Schedules published by NOAA NAVY OCEANOGRAPHIC DATA DISTRIBUTION SYSTEM The Navy Oceanographic Data Distribution System NODDS is a dial up data service available from FNMOC Although origi
121. ne the extensiveness or depth of a given feature RCS is also an excellent product for locating WERs BWERs and maximum reflectivity cores Figure 2 46 18 an example of the RCS product The selection and placement of the cross section 1s extremely important Even slight deviations often result in misanalysis of anticipated features hooks BWER etc Also be aware that targets displayed by RCS are not always meteorological but may be the result of birds insects etc Velocity Cross Section VCS Product When it comes to storm interrogation no analysis is complete without a thorough look at velocity data The Velocity Cross Section VCS product provides a vertical cross section of velocity data It 15 available in two different modes clear air and precipitation In clear air mode mode A the Vertical Cross Section VCS product can determine the existence and depth of turbulent layers and determine the intensity of wind shear Boundaries and frontal slopes are evident by significant changes in wind speed or direction These features are often more visible here rather than on an RCS product In precipitation mode mode B the existence strength and vertical depth of vortices areas of rotation are analyzed These may confirm the presence of mesocyclones or tornadoes and make a strong case for severe weather when linked to other products VCS is an excellent tool for determining divergence convergence and cyclonic and ant
122. ngle 2 43 Immediately upon the identification of a TVS you should notify the forecaster and turn your attention toward other products for further investigation e g base velocity As with the MESO product TVS should not be used as a stand alone source of information The algorithm of TVS searches only mesocyclones Tornadoes formed outside of mesocyclone bearing storms go undetected All limitations associated with the MESO product will also effect the TVS product Unfortunately the range of this product is limited to approximately 60 nmi Storm Track Information STI Product The Storm Track Information STI product monitors the position and movement of isolated 2 48 thunderstorms within a 250 nmi radius of the RDA It also estimates future movement of isolated storms These forecasts can be used to generate automated alerts STI monitors the movement of isolated storms by correlating each storm s current position to a storm found in the previous volume scan These storms are then related to each other in time and space If a storm cannot be correlated to the previous scan it is designated as new STI also provides users with best guess guidance on storm paths throughout the radar coverage area Each storm 15 assigned a unique alphanumeric identifier Movements are forecast in 15 minute increments for up to 1 hour represented by each tic mark The algorithm s internal confidence factor rates each storm AGM3F
123. nsor then assigns an intensity level from 0 to 256 for each pixel The size of the area field of view scanned by the sensor determines the spatial resolution of the overall image Thus the smaller the area scanned for each pixel the higher the spatial resolution Some sensors may scan an area as small as 0 5 km across high resolution while others scan areas as large as 16 km low resolution When composed into an 1mage smaller pixels allow the image to be much clearer and show greater detail Clouds and land boundaries appear better defined If objects are smaller than the sensor resolution the sensor averages the brightness or temperature of the object with the background Normally the sensors aboard satellites are able to provide better resolution for visual imagery than for infrared imagery DMSP satellites have very high resolution capabilities in both visual and infrared TYPES OF IMAGERY things with a temperature above absolute Zero emit radiation in the form of electromagnetic waves The wavelengths emitted by each object depend primarily on the object s temperature Higher temperatures cause electrons to vibrate faster and therefore produce shorter wavelengths The sun emits radiation at several different wavelengths and the range of these wavelengths is known as the electromagnetic spectrum fig 1 10 view A Electromagnetic wavelengths in the visual and infrared region are usually measured in micrometers A mic
124. nt with the appearance of a funnel cloud as viewed from below Studies suggest that TVSs are detectable 20 minutes prior to tornado touchdown on average Most TVSs detected by the WSR 88D are associated with tornadoes However not all tornadoes produce a TVS Like the mesocyclone product TVSs primary function is to alert users of high rotation and shear An area with possible tornadic activity 15 indicated by an inverted 17 241 THIS PAGE MUST BE PRINTED ON A COLOR PRINTER 2 Lo 5 4 T m 5 F om p 1 5 ae 5 5 1 i 4 2 A Figure 2 41 Severe Weather Probability product 2 21 24 SHF 47 SHF 124 HM 2 2 HM RES grar 28 57 3BH8 231 52H 1265 FT 34 19 44 MODE 2 ADEG i HM amp BOXxX 15 INM HD 1 35 58 1 1 CUMzI 015 HI 2118 FRODO RCUD VIL OT 2057 24 2124 LINE 3 REQUESTED DZCHCT HARDCOPY AGM3F242 03 29 98 28 18 MESOCYCLONE 60 M 230 KM 18 86 89 29 35714463N 1255 FT 977277438 MODE A 11 355DEG MAG 4 QUL AT JUL AH qi5 5 8534 PROD RCO RPS KOUM 8534 ALERT 29 2008 F CANCELLED HARDCOPY HARDCOPY REQUEST 28 ACCEPTED ALERTS 1 gt UM GL 2 FM UD Figure 2 42 Mesocyclone MESO product red tria
125. nterpretation and hardware troubleshooting support for the WSR 88D can be obtained through the Operational Support Facility OSF located in Norman Oklahoma The OSF maintains a 24 hour hotline to respond to technical problems and questions that may arise while operating any component of the WSR 88D A Naval Oceanographic Component has been assigned by the Naval Oceanographic Office to act as a liaison representative and to specifically assist any Navy Marine Corps activity that has a WSR 88D PUP It would be helpful to know the different users of the WSR 88D and how they interface with one another Let s begin by defining all WSR 88D system users fig 2 31 Principal Users Principal users of the WSR 88D are the National Weather Service NWS the Department of Defense DOD the Federal Aviation Administration FAA and the subagencies they represent Principal users can be further classified by their mode of access to the RPG Every principal user needs a PUP to access the RPG except PUES Associated Principal Users APUPs An associated principal user is the priority customer supported by each system Most Navy and Marine Corps weather offices are APUP sites APUPs gain RPG access through a dedicated narrowband link phone lines and generally reside within 100 nmi of the host RDA APUPs may request any product which the RPG 1 capable of producing even those that are unavailable to other principal users They may also re
126. nts from each pixel when composed into an image of the earth form an infrared image Most infrared satellite imagery is measured at wavelengths of 10 2 um to 12 8 um far infrared Some satellites are able to augment visual and far infrared imagery by also measuring near infrared NIR wavelengths 74 um to 2 0 um NIR imagery generally shows better land water contrast and 1 4 T i em MES v 4 simplifies low level feature identification such as shorelines snow ice and vegetation The satellite receiver and processor control how the composed image will look Normally the energy measurements for infrared image pixels are assigned g ray shades with low energy readings appearing white and high energy readings appearing black The lighter the gray shade the colder the object seen With IR images space surrounding the earth is white and warm land or water masses are dark gray or black Infrared imagery is an excellent tool for oceanographic analysis such as evaluating sea surface temperatures and determining ocean front and eddy locations It is also very helpful for identifying high clouds and upper level wind flow but less reliable for identifying low level features Look at figure 1 12 Notice how lower level clouds very distinct in the visual image are more difficult to determine in the Figure 1 12 GOES visual image on left compared to GOES infrared IR image on right Spa
127. oduct reliability RADAR PRODUCT GENERATOR RPG The RPG is considered the brains of the WSR 88D It is a bulky mainframe computer housed in what resembles an oversized wall locker 2 28 An alphanumeric input terminal allows user interface The RPG creates all WSR 88D radar products by performing sophisticated analyses of data through a multitude of computer programs called algorithms The RPG provides hundreds of new and unique products every 5 to 10 minutes Because of the vast quantities available products themselves are categorized as either base or derived products Base products are near real time images They display targets as seen by the radar during its most recent scan Derived products on the other hand are specialty products Derived products evolve from base products that have been modified or enhanced to produce special results Derived products are often used specifically to examine features that are not easily seen on base products We will discuss the more important base and derived products later Once products are built the RPG stores and distributes them according to predefined system commands In some cases the RPG is instructed to generate audible alarms alerts when special weather conditions are detected Once alerted users may examine conditions more thoroughly by using all available products Conditions that trigger these alerts are user definable and can be tailored to meet the mission of your
128. of the earth The satellite sensors scan the earth in horizontal lines starting near the North Pole and working down towards the South Pole Geostationary satellites are ideal for making large scale frequent observations of a fixed geographical area centered on the equator Thus they are better suited to track rapidly moving large scale disturbances in the atmosphere or to look closely at small scale or short duration changes in the atmosphere However their distance from the earth limits the resolution of the imagery In addition these satellites do not see the poles at all and to achieve global coverage of just the equatorial regions a network of 5 to 6 geostationary satellites is required Figure 1 5 khows atypical GOES satellite NORTH X RAY SENSOR Figure 1 5 GOES satellite TERME Fav ANK GOES AT 135 WEST 24 S PTA Ke A LL ake SD are am i ave EMITE AAT CAAT VAN mr am op S Nai RA USEFUL CAMERA COVERAGE NN RANGE GOES AT 75 EAST AGM3f 106 Figure 1 6 Data coverage of GOES East and GOES West satellites NOAA operates two geostationary satellites known as GOES East and GOES West The GOES East satellite currently GOES 8 is located over 75 west longitude while GOES West currently GOES 9 is located over 135 west longitude Figure 1 6 shows the area of the earth covered by GOES East an
129. oon moving slowly toward the antenna Unlike the stationary building the balloon s motion causes a change in the appearance of each successive wave If the radar observes these changes phase shifts it will realize that motion has occurred and can then convert this information into target velocity Keep in mind that the ability of a Doppler radar to detect phase shifts and compute velocity depends upon the system maintaining a consistent transmitter frequency and phase relationship from one pulse to the next RADIAL VELOCITY We know that Doppler radars can tell whether a target is moving toward or away from the radar Doppler radars can also measure the velocity of the target toward or away from the antenna Take a look at At time T1 a pulse is sent towards a target and it returns at target distance Y At time T2 another pulse is sent towards the same target and returns a target distance of Y Z The distance to the target has changed from time to T2 resulting in a phase shift between the two return signals By measuring the phase shift the wavelength and the time interval from T1 to T2 the velocity the target moved toward or away from the radar can be computed By convention motion towards a Doppler radar is expressed in negative values and green cool colors on a display screen Motion away from a Doppler radar is expressed in positive values and red warm colors The WSR 88D s sensitivity enables it to detect extre
130. ow enhancement curves two ranges are selected For each of these a unique part of the gray shade and count value scale 15 applied to each range Thus warm temperatures may be in the gray black range while cold temperatures may be in the white off white range is an example of a high low enhancement curve with temperature ranges of 30 to 05 and 20 to 40 Areas colder than the lowest minimum temperature will appear white Areas warmer than the highest maximum temperature will appear black Areas which are temperatures between the upper and lower ranges will appear black 1 16 COUNT VALUE INPUT WHITE 000 100 150 G R A Y S C A L E ACVACO mcr gt lt 0 7 18 2 255 0 TEMPERATURE AGM3f116 Figure 1 16 Single enhancement curve COUNT VALUE INPUT WHITE 000 100 150 mr o0 mo HC U HCO mcr AZCOO 000 3 0 7 67 3 165 3 F 8 18 2 55 2 110 2 0 255 0 218 0 163 0 44 6 280 TEMPERATURE 31117 Figure 1 17 High low enhancement curve 1 17 SPLIT ENHANCEMENT For split enhancements two ranges are also selected For each the complete gray shade and count value scale applies This means that the complete gray shade scale 1 applied twice over the image except for temperatures lying between the two defined ranges Figure 1 18 displays a split enhancement curve for temperatures of 30 C to 0 and 10 C to 30 C Areas colder than the
131. oximately 810 pulses per second This would cause the maximum unambiguous velocity to decrease to 45 mph The Doppler Dilemma is caused by physical restrictions based on the laws of nature One of the ways the WSR 88D works around this dilemma is to operate at variable PRFs collecting reflectivity information at low PRFS and velocity information at high PRFs The two sets of information collected are compared and processed to estimate true radial velocities and ranges Range Versus Height The WSR 88D samples through 360 at a series of fixed elevation angles At each elevation angle the distance outward along the radar beam represents an increase in height above the ground In other words the further you move away from the antenna the higher the beam is off the ground You must remember that the very center of a product display represents only the height of the radar tower while the outer edges of the display are thousands of feet above the ground You can now see how the WSR 88D gives you a pseudo three dimensional display REVIEW QUESTIONS 033 Doppler is used to measure what property 034 What are some of the advantages of the WSR SSD over conventional weather radars 035 What happens to a return frequency when a target moves toward a radar Q36 What is a phase shift Q37 The phase of a wave is measured in what units Q38 Which three measurements are required to compute radial velocity 039 How is the detect
132. pace available basis External Users External users consist of anyone other than a principal user External users are normally non governmental agencies who are authorized access to WSR 88D data and products These agencies may include news media private weather services broadcast meteorologists airlines universities aviation facilities commercial contractors and more These organizations generally pay for dial in access and their product selection is severely limited Specialty products are unavailable to external users and cannot be requested SYSTEM COMMUNICATIONS Good communications is the backbone of any complicated computer network and the WSR 88D is no exception The WSR 88D communications system consists of two bands that fuse individual components into one efficiently run operation The two bands wideband and narrowband are designed to quickly route data and products between components and users Wideband Wideband is a high speed link between the RDA and RPG used to transfer massive amounts of data quickly refer back to fig 2 25 It also conveys system commands to the RDA recall system commands originate at the UCP Should this crucial link be broken all antenna functions halt the processing of real time data ceases and communications to and from the RDA are terminated Wideband link may consist of either hard wired direct cabling to the RPG or a fiber optic connection The type of connection used
133. played and studied The various other display options such as map overlay and enhancement are menu driven for both the GTIS and MIDDS as 1 the channel selection Instructions for using GTIS are contained in the User s Manual provided with each installation The MIDDS has a colorized custom enhancement function and a few systems have the additional capa bility of obtaining satellite images via WEFAX broadcast HF radio or Automatic Picture Transmission APT receiver Instructions for obtain ing satellite information via MIDDS is contained in the Meteorology and Oceanography METOC Integrated Data Display System MIDDS User s Guide DIRECT READOUT SERVICE Direct readout service is an image data transmission designed to be received by user operated satellite receiver stations such as the AN SMQ 11 satellite terminal and the Interim Mobile Oceanography Support System IMOSS satellite module The raw satellite signals are converted to an image by the receiver station Direct readout service 1 available from all polar orbiting meteorological satellites This service is generally not available from geostationary satellites although a few weather activities have acquired geostationary direct readout systems from commercial contractors One type of direct readout service that is provided by the NOAA satellites is the Automatic Picture Transmission APT service APT service provides a continuous transmission of both visual and in
134. provide higher dBZ values hail or drizzle 046 The RDA is capable of reducing or eliminating what type s of radar problems Which component of the WSR 8SD contains algorithms that create products 047 Q48 What is the difference between base products and derived products Which component of the WSR 88D does the observer or forecaster use to request and obtain products 049 Q50 What is the primary input device when operating PUP workstation Q51 Most Navy and Marine Corps stations with Principal User Processor PUP workstations are classified as being what type of WSR 858D system user 052 WSR 68D narrowband links are maintained by what mode of communication Q53 Data available at the PUP workstation is recorded at which archive level Q54 What is meant by the term volumetric product Q55 Which operational mode and volume coverage pattern should be selected when severe weather is present or expected WSR 88D PRODUCTS LEARNING OBJECTIVES Identify how WSR 88D products are acquired Recognize the difference between base data and derived data Identify the more commonly used base and derived products Identify the uses and limitations of base and derived products 2 33 In this section we will explain how products are acquired from the WSR 88D Next we discuss in detail the difference between base and derived data We then examine some of the most commonly used products
135. quest the creation of unique products even if such requests result in increased RPG workload While are connected via dedicated link they re APUPs SYSTEM USERS NEG EXTERNAL PUES AGM3F231 USERS Figure 2 31 WSR 88D system users 2 30 furnished with the option to dial in via commercial telephone lines This enables continued receipt of products in emergency backup situations APUPs exercising this option lose their associated status and become non associated user NAPUP Non associated Principal Users NAPUPs Non associated principal users are identified as customers that dial in for access NAPUPs experience more restrictions than an APUP would NAPUPs cannot request specialty products nor can they increase RPG workload in any fashion In fact even routine products maps and overlays might be unavailable to NAPUPs restrictions vary from system to system Principal Users External Sources PUES PUES are defined as principal users who access RPGs through nonstandard means In other words they do not use a PUP to interface with the RPG The AFWA is only one of many PUES The AFWA is a primary user that requires access to hundreds of radars each hour Its mission is to mass produce charts for DOD weather stations around the globe In this example the customer s own computer meets their needs more efficiently than a PUP would All PUES are granted RPG access through reserved ports on a s
136. r prescribed listening time the radar assumes no targets were encountered and that the pulse has continued on its outward direction Listening time determines a radar s maximum effective range as it in effect limits the distance a pulse can travel If listening time 15 reduced pulses can cover less distance and effective range is decreased Thus a 50 percent reduction in listening time cuts maximum radar range in half Only targets within the maximum effective range are detectable sient PERIOD AGM3F207 PULSE LENGTH Figure 2 7 Radar Pulses 2 6 Range Ambiguity As described earlier the pulse repetition frequency largely determines the maximum range of the radar set If the period between successive pulses 1 too short an echo from a distant target may return after the transmitter has emitted another pulse This would make it impossible to tell whether the observed pulse is the echo of the pulse just transmitted or the echo of the preceding pulse This produces a situation referred to as range ambiguity The radar 1 unable to distinguish between pulses and derives range information that 1s ambiguous unreliable In theory it 1s best to strike a target with as many pulses of energy as possible during a given scan Thus the higher the PRF the better A high PRF improves resolution and range accuracy by sampling the position of the target more often Since PRF can limit maximum range a compromise is reached by s
137. r network AWN They are also 1 3 available on the meteorological oceanographic data channel of the fleet multichannel communications broadcast as well as via AUTODIN message TBUS data can also be obtained from the Internet through the NOAASIS website The TBUS bulletins are in a special U S national code form The code form is only used for orbital prediction information for satellites operated by the United States Complete information on this code 1s available in the NOAA KLM User s Guide Satellites in the TBUS bulletin are identified in the message header by name such as 14 and by the U S satellite identification number such as 37 for NOAA 12 and 38 for NOAA 14 In Part IV of the bulletin the satellites are identified by an internationally recognized satellite number such as 1994 089A for 14 A separate NOAA predict bulletin 1 composed daily for each operational NOAA series satellite TBUS 1 bulletins are used to indicate north to south descending daylight orbits and TBUS 2 bulletins are used to indicate south to north ascending daylight orbits Each bulletin is composed of six parts e Part I contains equator crossing reference information Day Part II contains satellite altitude and subpoint coordinates in 2 minute intervals for reference orbits over the Northern Hemisphere in the sunlight portion Day Part III contains the altitude and subpoint coordinates for the portion of the
138. rbit This change in position 1 called the nodal increment 1 2 The total time it takes the satellite to complete an orbit is called the nodal period The term epoch refers to a specific reference point in a satellite s orbit Most polar orbiting environmental satellites use a nodal increment and a nodal period that keep pace with the rotation of the earth and keep the satellite path crossing the equator at the same local mean time POLAR ORBITS INCLINATION 105 NORTH POLE 7 EQUATORIAL STATIONARY ORBIT SATELLITE 0 INCLINATION ud SOUTH POLE 76 POLAR ORBITING SATELLITE AGMf101 Figure 1 1 Satellite inclination ARAN TANE mit AV 150 140 130 120 110 100 90 804 70 60 50 40 WEST 1102 Figure 1 2 Nodal increment the westward change in position of polar orbiting satellite s path on earth on successive orbits 1 2 LMT during each orbit These types of orbits are called sun synchronous orbits they are synchronized with the movement of the sun across the earth s surface For instance an orbit may be calculated so that the satellite path crosses the equator on the descending node 2 hours after sunrise on each orbit The ascending and descending nodes may additionally be identified by the relative time of day such as day ascending day descending night ascending or night descen
139. re always compromises between simple enhancement curves which sacrifice detail but can quickly be interpreted in an operational environment and complex curves which maximize information content but require more time to interpret is a graphic illustration of a basic enhancement curve table Count values as input would be plotted on the horizontal axis and modified count values for the final display would be plotted on the vertical axis These count values range from 0 to 255 where 0 appears as black and 255 appears as white Values in between produce varying shades of gray By adding deleting and positioning points within the graph an input color or gray shade is mapped to an output color or gray shade As points of reference six count values on the horizontal axis correspond to the six sets of temperatures at the bottom of the graph Count values on the vertical axis result in the gray shade range as referenced at the right of the graph The 1 14 25 TEMPERATURE TEMPERATURE c 30 20 Figure 1 14 Processed GOES infrared images with temperatures added to gray shade scale A A predefined ZA enhancement straight black to white shading and B a predefined enhancement used to better define cloud top temperatures cloud height in thunderstorms at points A B and C 1 15 COUNT VALUE INPUT 000 050 10 C 150 200 E WHITE C G N R T V A S L C U A E E
140. re ambiguous The radar is unsure if motion 1 inbound toward the antenna at 60 knots or outbound at 40 knots Look figure 2 24 In views and B the target s motion poses no problem to the radar as both motions produce phase shifts of less than 180 one half wavelength regardless of direction Illustration C depicts a phase shift of 180 Here 1 where the A Figure 2 23 A Speedometer showing true velocity B Speedometer showing ambiguous velocity 2 20 problems begin Remember that to unambiguously measure the phase shift the shift must be less than one half the wavelength 180 In this case we cannot distinguish whether the 180 shift represents motion toward or away from the radar This measurement is ambiguous Illustration D depicts a phase shift of 270 resulting from energy striking a target that is moving away from the radar Since a shift of 270 1 more than one half wavelength 180 it 1s ambiguous This 270 shift 15 seen as a 90 phase shift of motion toward the radar This can result in an aliased velocity being displayed While aliased velocities are subject to misinterpretation the WSR 88D has a unique way of dealing with them Computer programs are designed to recognize that direction reversal 15 impossible They determine that wind speeds are exceeding radar tolerance and calculate the amount of aliasing occurring All necessary corrections are then applied to the produc
141. re generated because the sun radiates energy in the same region of the electromagnetic spectrum as the WSR 88D These echoes are recognized by their continuous narrow baseball bat appearance REVIEW QUESTIONS Q25 What is refraction Q26 What atmospheric parameter has the greatest impact on refraction and refractivity Q27 What normally happens to N units with increasing altitude 028 radar beam is consistently overshooting targets which refractive condition might be present Q29 The phenomenon of ducting is most likely to occur under what atmospheric condition Q30 What is the cause of ground clutter 031 What type of scattering is NOT attenuation Q32 What are the main absorbers of EM energy in the atmosphere PRINCIPLES OF DOPPLER RADAR LEARNING OBJECTIVES Define Doppler and Doppler shift Define phase shift and radial velocity Recognize the effects of target motion on radial velocity Define velocity aliasing Recognize the effects of velocity aliasing on Doppler radar Compute Nyquist velocity Identify Doppler dilemma 2 16 So far we have discussed basic principles of electromagnetic energy common to all radar systems The following text expands on the theory and principles already discussed and introduces concepts unique to Doppler radar Doppler is a means to measure motion Doppler radars not only detect and measure the power received from a target they also measure the motion of the t
142. reference orbits over the Southern Hemisphere in the sunlight portion Night Part II contains 2 minute coordinates for the portion of the orbit over the Northern Hemisphere in the dark sector Night Part III contains coordinates for the portion of the orbit over the Southern Hemisphere in the dark sector Part IV contains high precision orbital calculation elements transmission frequencies and remarks Parts II and III day and night are useful only when satellite orbits must be manually plotted and will not bediscussed further TESS requires information from both Parts I and IV while the SAT MOD and AN SMQ 11 require only information from Part IV Table 1 2 Typical NOAA Predict Bulletin TBUS 2 KWBC 021900 APT PREDICT MMDDSS 010538 NOAA 14 PARTI ON NrNrNr 0D DrHrHr OMrMrSrSr QrLoLoLoLo Tmmss LLoLoLoLo 05551 00515 05539 02127 T0203 L2551 Reference Orbit N4N4N4N4H4 Hama4mas 4s4 QaLoLoLoLo 55552 24353 12333 Fourth Orbit N amp 8N8NsN Hs Hagmgmsssss QsLoLoLoLo 55590 53207 23461 Eighth Orbit N12N12N12N12H12 H12m12m12812812 Qi2LoLoLoLo 55631 22021 33255 Twelfth Orbit DAY PART IL DAY PART III NIGHT PART II NIGHT PART III PART IV AAAAAAAAA CCCCCCCCCCCC DDEEFFGGHHIIIII JJJJJJJ 1994 089A 15472 365064564372 971231013258362 1227653 KKKKKKKK LLLLLLLL MMMMMMMM NNNNNNNN 01020047 01020594 00098964 09699662 31704580 09902079 00000000
143. referred to as NOAA POES NOAA Polar orbiting Operational Environmental Satellite compares various characteristics between geostationary and polar orbiting satellites Polar Orbiting 12 hours Good 2 700 km strip At receiving station Inexpensive 3 4 years DMSP SATELLITES DMSP satellites polar orbiting satellites managed by the Department of Defense that provide very high resolution imagery These satellites can provide real time worldwide support to operating forces for both shipboard and selected shore sites Near real time stored environmental imagery can also be provided by the Fleet Numerical Meteorology and Oceanography Command FNMOC at Monterey California Because imagery from DMSP satellites is encrypted for transmission special processing equipment 1 required for download Each direct transmission received from DMSP contains two channels visible and infrared The channels are transmitted so that one channel will provide fine data 0 56 km resolution and the other will provide smooth data 2 7 km resolution Unique sensors aboard DMSP satellites allow for the collection of visual imagery at night by using lunar illumination The determination of channel assignment is made by the Air Force Weather Agency located at Offutt AFB Nebraska DMSP satellites also have a special passive microwave sensor known as a SSM I Special Sensor Microwave Imager S
144. rimary satellite receiver systems used to acquire direct readout imagery and WEFAX products Identify the operator s manuals that provide detailed instructions for use of the systems Two satellite receiver systems are routinely operated by Navy and Marine Corps weather observers The AN SMQ 11 system is used at major shore installations and aboard all aircraft carriers Navy Mobile Environmental Teams METS use the optional satellite module of the IMOSS to receive satellite imagery AN SMQ 11 METEOROLOGICAL DATA SET The AN SMQ 11 satellite receiver station 15 installed aboard most U S Navy ships staffed by Aerographer s Mates at many Naval Meteorology and Oceanography Command activities and in Marine Corps Mobile Meteorological Vans METVANSs The 11 may receive process display grid and enhance DMSP imagery and both APT and HRPT direct readout imagery The system can also receive WEFAX imagery but cannot command a data download of stored HRPT data AN SMQ 11 produces imagery on dry silver film which requires no chemicals for development or by using a high resolution laser printer shows the two AN SMQ 11 equipment cabinets that are installed inside the workspaces Each AN SMQ 11 is equipped with a Tactical Advanced Computer Version Four TAC 4 that includes a workstation color monitor an uninterruptible power supply and a power distribution unit The ANLSMQ 11B has a dual frequency array antenn
145. rning all these components is the radar s sensitivity A radar s sensitivity or signal to noise ratio is a measure of the MODULATOR TRANSMITTER SIGNAL PROCESSOR interference generated by the radar self noise against the minimum signal it is able to detect REVIEW QUESTIONS 08 What is meant by the term reflectivity Q9 Which part of a radar system shapes energy into a beam 010 What is meant by the term radar sensitivity PRINCIPLES OF RADAR PROPAGATION LEARNING OBJECTIVES Distinguish various radar pulse characteristics including pulse length listening time range ambiguity range folding and pulse volume Define range resolution and pulse repetition frequency Compute Rmax Recognize the effects of beamwidth beam broadening and sidelobes on radar energy Define azimuthal and range resolution Rather than transmit one long continuous wave CW weather radar uses short powerful bursts of energy called pulses Pulsed energy travels along a focused path called a beam and occupies a specific amount of space Pulses are separated by silent periods that allow the antenna to listen for a return pulse The information gained from these pulses is critical in DUPLEXER ANTENNA RECEIVER AGM3F206 Figure 2 6 Block diagram for a simple radar system determining target size strength and location 2 7 RADAR PULSE CHARACTERISTICS Radar pulses travel at the speed of light 186 000 miles per second
146. rometer is equal to one millionth of a meter and is represented by the symbol um Micrometers are also referred to as microns The sun emits a maximum amount of radiation at wavelengths near 0 5 um The earth which is obviously much cooler emits most of its radiation at longer wavelengths of between 4 and 25 um For this reason the earths radiation 1 referred to long wave radiation and the sun s energy is referred to as shortwave radiation The atmosphere is a strong absorber of radiation at certain wavelengths and is relatively transparent to others Generally the atmosphere 1 transparent to wavelengths associated with incoming solar radiation but because of the presence of water vapor carbon dioxide and other elements the atmosphere 1s largely opaque to the outgoing terrestrial wavelengths When data signals from a satellite sensor scan are compiled at the satellite receiver on earth the pixels and scan lines form an image The image composed of measurements of energy in the visual range forms a visual image The data from sensors that measure energy in the infrared band compose an infrared image ELECTROMAGNETIC SPECTRUM lt 003 um 01 4 um WAVELENGTH GAMMA RAYS X RAYS UV VISIBLE 4 7 um EXTREME U V AND X RAYS VISIBLE 1 5 um 1 mm INFARED MICROWAVE VHF NEAR INFRARED 7 15 SCHEMATIC DIAGRAM THE DISTRIBUTION OF ENERGY IN TH
147. ronmental parameters such as sea surface temperature wave height snow ice cover low level wind speed and direction and ozone distribution Although these functions are very important to meteorology and oceanography you will not normally be involved in this type of data collection or data processing In this module we discuss only the differences in satellites that are important to you in acquiring satellite imagery In the United States both the U S Department of Commerce and the U S Department of Defense operate meteorological satellite programs The National Oceanic and Atmospheric Administration NOAA a division under the Department of Commerce operates its satellite programs through the S BAND TRANSMIT ANTENNA S BAND RECEIVE ANTENNA EARTH SENSORS T amp C ANTENNA SAR ANTENNA TRIM TAB National Environmental Satellite Data and Information Service NESDIS Their primary meteorological satellite programs are the Geostationary Operational Environmental Satellite GOES and the Advanced Television InfraRed Observation Satellite NOAA ATN polar orbiter also called a TIROS N or NOAA satellite Both systems are energized with solar power while in orbit The Department of Defense oversees the Defense Meteorological Satellite Program usually referred to as the DMSP GEOSTATIONARY SATELLITES Geostationary satellites are placed at an altitude 35 800 km where their orbital period exactly matches the rotation
148. s since the WSR 88D has a fixed wavelength of 10 7 cm we can compute the Nyquist velocity Vmax for any given PRF from the following formula Vinax PRF x Wavelength 4 For example a WSR 88D radar operating with a PRF of 1000 would have a Nyquist velocity of 52 knots This is found by multiplying 1000 by 10 7 and dividing by four 2675 cm sec This can then be converted to 26 75 meters per second 100 centimeters in a meter Multiply this value by 1 94 to convert to knots From this formula you can see that higher PRFs yield higher maximum 2 2 detectable velocities and that lower PRFs will increase the chances of velocity aliasing Doppler Dilemma We learned earlier that Doppler radar 1 subject to range folding This resulted when the radar detected a previous pulse while listening for the most recent pulse Reducing the pulse repetition frequency PRF and allowing for a longer listening time will alleviate the problem of range folding However as just discussed low PRFs may then lead to the problem of velocity aliasing These two difficulties combine to define what is known as the Doppler dilemma For example in order for the WSR 88D to detect radial velocities of 200 mph without aliasing the PRF would have to be increased to about 4 000 pulses per second However this would reduce the maximum unambiguous range of the radar to about 20 nmi To have an unambiguous range of 100 nmi the PRF would have to be appr
149. s not sense each individual motion but rather a combination of all velocities for the overall sample This combination of different velocities is what spectrum width measures Spectrum width data 1s quite useful in determining atmospheric stability and 1 a good indicator of environmental turbulence By itself it offers very little guidance Combined with other products the user can determine radar performance and reliability of the data being displayed The concept of evaluating spectrum width data 1 still relatively new and operational uses are still being developed RDA Subcomponents The RDA consists of all the hardware and software needed to transmit and receive radar energy It also preprocesses raw data by filtering inconsistencies The transmitter receiver and signal processor are housed together in a small building near the antenna as pictured in figure 2 26 These components together with the antenna make up the RDA Only a single RDA exists for each system ANTENNA The WSR 88D uses a 28 ft dish shaped antenna to focus radar energy along a concentrated beam This same antenna is used to receive backscattered energy from targets and atmospheric scatterers PEDESTAL A cast aluminum structure that secures the antenna to the top of a 98 ft steel tower The Y r ft WM a sow Ad QJ k a B alu Cag ie mn js ye Qi m E i E n 4 LA m 2
150. s of the products available from the WSR 88D Al A2 4 A3 AJ A9 A10 12 A13 A14 15 A16 17 18 19 A20 ANSWERS TO REVIEW QUESTIONS An electromagnetic wave is radiation energy in the form of a sine wave with both electrical and magnetic properties Radio microwave region Centimeters or degrees Shorter wavelengths provide finer detail Longer wavelengths are more effective when evaluating larger targets Frequency is the number of completed wave cycles per second measured hertz 100 GHz By using the decibel system Reflectivity is the amount of energy returned from an object and is dependent on the size shape and composition of the object The antenna The sensitivity of a radar is the measure of the radar s internal interference against the minimum signal it is designed to detect Longer pulses return more power thus increased target information and data reliability In seconads or kilometers Resolution refers to the ability of the radar to display multiple targets clearly and separately The rate at which pulses are transmitted per second An increase in PRF provides greater target detail however the maximum range of the radar is reduced The inability of the radar to distinguish between return pulses producing ambiguous unreliable range information 93 miles 81 nmi A pulse from a distance outsi
151. t target From this we learn why it s impossible for the radar to tell where one pulse ends and another begins The radar sees one continuous signal The slightest increase in target separation will overcome this limitation and enable the radar to display both targets correctly AGM3F213 Figure 2 13 Azimuthal resolution and target stretching 2 10 011 012 013 014 015 016 017 018 019 020 021 a A B D AGM3F214 Figure 2 14 Pulse length versus range resolution REVIEW QUESTIONS Q22 How does the presence of sidelobes affect radar How does pulse length affect the amount of performance energy returned from each pulse Q23 What is the main cause of degraded azimuthal Pulse length is usually measured in what units resolution What is described by the term resolution Q24 What is the main radar characteristic affecting What is a radar s pulse repetition frequency range resolution What happens when a radar s PBF is increased FACTORS AFFECTING RADAR What is meant by the term range ambiguity PROPAGATION If a radar had a pulse repetition frequency PRF of 1000 what would be its maximum unambiguous range LEARNING OBJECTIVES Define refraction What causes the phenomena of range folding 7 and refractive index Recognize the effects of refractivity on radar systems Identify effects of subrefraction superrefraction and ducting on radar systems
152. t stream are easily identified using WV imagery REVIEW QUESTIONS 015 What is the image scanning sensor of a satellite called 16 Which sensor would provide higher resolution data one with a spatial resolution of 1 kilometer or one with a spatial resolution of 4 kilometers 017 Consider two objects one cold the other hot Which object is emitting electromagnetic energy at relatively longer wavelengths 018 The majority of the radiation emitted by the earth is known by what term QI9 In the visible spectrum what color has the longest wavelength Q20 Of the following objects sand or grass which one would have a higher albedo Q21 What are the major advantages of infrared imagery Q22 How do relatively cold objects appear on IR imagery Q23 How do high humidity areas appear on water vapor images Q24 What are the advantages of water vapor imagery IMAGERY ENHANCEMENT LEARNING OBJECTIVES Identify various types of user defined and predefined satellite enhancement curves Identify information contained in the GOES legend and temperature scale Most satellite data processors have the capability to assign colors or various gray shades to specific JR imagery energy readings When an image is produced by using either color or an alternating gray shade rather than the straight black to white or white to black shading the color or gray shade assignment 1s called an enhancement An enhanced satellite image al
153. t working day approximately 24 hours In addition to receiving grade results for each assignment you will receive course completion confirmation once you have completed all the vi assignments To submit your answers via the Internet go to assignment http courses cnet navy mil Grading by Mail When you submit answer sheets by mail send all of your assignments at one time Do NOT submit individual answer sheets for grading Mail all of your assignments in an envelope which you either provide yourself or obtain from your nearest Educational Services Officer ESO Submit answer sheets to COMMANDING OFFICER NETPDTC N331 6490 SAUFLEY FIELD ROAD PENSACOLA FL 32559 5000 Answer Sheets All courses include one scannable answer sheet for each assignment These answer sheets are preprinted with your SSN name assignment number and course number Explanations for completing the answer sheets are on the answer sheet Do not use answer sheet reproductions Use only the original answer sheets that we provide reproductions will not work with our scanning equipment and cannot be processed Follow the instructions for marking your answers on the answer sheet Be sure that blocks 1 2 and 3 are filled in correctly This information is necessary for your course to be properly processed and for you to receive credit for your work COMPLETION TIME Courses must be completed within 12 months from the date of enrollment
154. tact and do not inhale the vapors and gases from these distillates Asphalt contains components suspected of causing cancer Anyone handling asphalt must be trained to handle it in a safe manner Hazardous materials require careful handling storage and disposal PMS documentation provides hazard warnings or refers the maintenance man to the Hazardous Materials User s Guide Material Safety Data Sheets MSDS also provide safety precautions for hazardous materials All commands are required to have an MSDS for each hazardous material they have in their inventory You must be familiar with the dangers associated with the hazardous materials you use in your work Additional information is available from you command s Hazardous Material Coordinator OPNAVINST 4110 2 series Hazardous Material Control and Management contains detailed information on the hazardous material program Recent legislation and updated Navy directives implemented tighter constraints on environmental pollution and hazardous waste disposal OPNAVINST 5090 1 series Environmental and Natural Resources Program Manual provides detailed information Your command must comply with federal state and local environmental regulations during any type of construction and demolition Your supervisor will provide training on environmental compliance Cautions and warnings of potentially hazardous situations or conditions are highlighted where needed in each chapter of this TRAMAN Rem
155. tain imagery from the European METEOSAT Yet another channel may contain high resolution picture transmission HRPT imagery from a NOAA satellite Enhanced infrared imagery from GOES is also routinely available via GOES TAP Most GOES TAP data is processed and analyzed by using a desktop computer with a color video monitor The monitor is used to display both the imagery and the control menus Initial issue equipment was the GOES TAP Imaging System GTIS which used a Unisys 80386 desktop computer Most of these systems have been replaced by the Meteorology and Oceanography METOC Integrated Data Display System MIDDS A laser printer may be connected to either system to provide hard copy prints of the imagery Although hard copies of selected images may be made hard copy quality 1s a function of the printer or imagery connected to the system Similar equipment called the Naval Satellite Display System Enhanced or NSDS E is used at most NAVMETOCCOM centers This system has the additional capability of copying NOAA polar orbiter and DMSP imagery Further changes to GOES TAP processing equipment are very likely in the future 1 22 Almost all satellite imagery processors have looper capability The primary application of any looper system is to store and display a series of geostationary satellite images of the same area a sequence that shows the movement of clouds and weather systems Individual satellite images may also be dis
156. te cloud heights bases tops the thickness of cloud layers and the height of the freezing level altitude at which the air temperature equals 0 C In addition reflectivity can also be used to locate the melting level The melting level is very close to and just below the freezing level therefore the melting level 1 slightly warmer As frozen particles descend through the melting level they become lightly coated 2 37 with water This makes them highly reflective and produces returns that are stronger than either the frozen particles above or the liquid droplets below When stratiform clouds are present the melting level appears as a halo around the RDA referred to as the bright band Keep in mind that the presence of either ground clutter anomalous propagation or hail can significantly contaminate reflectivity data and all products built from such data The Base Reflectivity product may be severely biased resulting in exaggerated intensities The product can become deceiving indicating the presence of strong storms which may or may not be real Range folded areas can also cause misinterpretation or obscure valuable data eo E gt ANNA NT NENNEN Re 2 CAMIS AGM3F235 Figure 2 35 Line Echo Wave Pattern LEWP Uneven acceleration causes the line to crest at position 1 and bulge at the point of acceleration position 2 beneath the purple shaded areas And as with all radar products suc
157. the TBUS bulletin The message 1 divided into 16 elements and can be input into the SAT MOD and AN SMQ 11 in lieu of data Keep in mind that while similarly named elements appear in both the NASA Two Line and TBUS bulletins the values are NOT interchangeable between systems to compute satellite tracks Table 1 4 is an example of a NASA Two line bulletin and table 1 5 is a description of the information NAVSPASURCEN ORBITAL DATA The Naval Space Surveillance Center NAVSPASURCEN in Dahlgren Virginia tracks all U S and foreign operated satellites and space debris Navy and Marine Corps satellite receiver system users may request message support for satellite tracking information The AN SMQ 11 contains software designed to use and interpet separate messages of data known as Satellite Equator Crossings TESS uses a product known as C Element Orbital Data to calculate orbits for the AN SMQ 11 A Satellite Equator Crossings message contains information similar to TBUS Part I The AN SMQ 11 needs to be updated frequently about every 2 days by using the information from this product The message contains information on all U S and foreign operated environmental satellites Table 1 6 contains a portion of a Satellite Equator Crossings message with explanations of the elements required to update the AN SMQ 11 The underlined elements are required Input C Element orbital data also contains information similar to Part IV of the
158. ther Radar This module describes the various type of environmental satellites satellite imagery and associated terminology It also discusses satellite receiving equipment addition Module 3 contains information on the Weather Surveillance Radar 1988 Doppler WSR 88D It includes a discussion of electromagnetic energy and radar propagation theory and explains the basic principles of Doppler radar The module also describes the configuration and operation of the WSR 88D as well as WSR 88D products AG MODULE 4 NAVEDTRA 14272 Environmental Communications and Administration This module covers several of the most widely used environmental communications systems within the METOC community It also describes the software programs and products associated with these systems The module concludes with a discussion of basic administration procedures NOTE Additional modules of the AG training series are in development Check the NETPDTC website for details at http www cnet navy mil netpdtc nac neas htm For ordering information check NAVEDTRA 12061 Catalog of Nonresident Training Courses which is also available on the NETPDTC website SAFETY PRECAUTIONS Safety 15 a paramount concern for all personnel Many of the Naval Ship s Technical Manuals manufacturer s technical manuals and every Planned Maintenance System PMS maintenance requirement card MRC include safety precautions Additionally OPNAVINST 5100 19 series Na
159. ther the occupational or naval standards which are listed in the Manual of Navy Enlisted Manpower Personnel Classifications and Occupational Standards NAVPERS 18068 THE QUESTIONS The questions that appear in this course are designed to help you understand the material in the text VALUE In completing this course you will improve your military and professional knowledge Importantly it can also help you study for the Navy wide advancement in rate examination If you are studying and discover a reference in the text to another publication for further information look it up 1999 Edition Prepared by AGC SW Stephen M Volpe AGC SW Daniel T Hoffman Published by NAV AL EDUCATION AND TRAINING PROFESSIONAL DEVELOPMENT AND TECHNOLOGY CENTER NAVSUP Logistics Tracking Number 0504 LP 026 9020 Sailor s Creed am a United States Sailor will support and defend the Constitution of the United States of America and will obey the orders of those appointed over me represent the fighting spirit of the Navy and those who have gone before me to defend freedom and democracy around the world proudly serve my country s Navy combat team with honor courage and commitment am committed to excellence and the fair treatment of all CONTENTS CHAPTER PAGE Environmental Satellites 1 1 Weather ceea sa e 2 1 APPENDIX 1 of the
160. ts you receive Nyquist Velocity As just explained velocity detection is wavelength dependent As soon as the one half wavelength limit 15 passed the determination of velocity becomes ambiguous Anytime we speak of wavelength the same arguments hold for frequency since they are inversely related Ultimately the pulse repetition frequency PRF of a radar determines the maximum speed that can be detected without confusion The maximum unambiguous velocity that can be detected at a given PRF 1 called the Nyquist velocity Nyquist 223 TRANSMITTED ENERGY AGM3F224 RECEIVED ENERGY UN SILI f f 90 OF PHASE SHIFT AWAY 9 90 OF PHASE SHIFT TOWARD XXX 180 OF PHASE SHIFT id yor es C NY LM Os A 1 M ptt DOO seer 270 M PHASE SHIFT AT M AS 90 OF PHASE SHIFT TOWARD Figure 2 24 Several phase shifts A 90 of phase shift away B 90 of phase shift toward C 180 of phase shift D 270 of phase shift away SEEN AS 90 of phase shift toward intervals are those velocities from zero up to and including the Nyquist velocity The Nyquist co interval 1 the entire range of detectable velocities both negative and positive For example if the Nyquist velocity is 25 knots then the Nyquist interval is any velocity from 0 25 knots and the Nyquist co interval is 25 through 25 knot
161. uces a form of radar nearsightedness As the beam diameter increases with distance closely spaced targets may occupy the beam simultaneously and 940 2 ape at E 7 at E Figure 2 11 Radar beam broadening AGM3F211 appear as one echo In short multiple targets at a distance are difficult to see correctly Sidelobes In addition to the main beam antennas produce rays of energy called sidelobes which surround the main beam primary lobe like haloes fig 2 12 Sidelobes extend outward only a short distance from the radar and contain very low power densities However even though they are weak sidelobes can detect strong non meteorological targets near the radar and are also disturbed by nearby g round reflections This leads to confusion in interpreting close targets because sidelobe targets are displayed along with the main beam targets RADAR RESOLUTION Radar resolution 1 the radar s ability to display targets correctly Both azimuthal resolution and range resolution are problems that commonly effect all radars Recall our earlier discussion about distant objects and their distorted appearance Resolution affects radar much the same way SIDE LOBES d ace ANGULAR BEAM WIDTH Azimuthal Resolution Azimuthal resolution
162. ulletin 1 not available directly from a disk file the system may be updated with manual entries by using information in the TBUS bulletins Only certain elements from each TBUS bulletin are required for each satellite in the SAT MOD The resulting ephemeris files need only be updated every 2 weeks Instructions for imputing TBUS bulletin data is contained in the IMOSS user s guide TESS Ephemeris Updates TESS allows satellite ephemeris data files to be updated manually by entering selected data via the keyboard TESS interfaced with a communications system may be directed to read a saved TBUS message file to automatically update ephemeris information TESS may only use each particular TBUS bulletin during a 7 day valid period following the prediction date in this case January 05 to January 12 Since predict bulletins are sent out daily TESS may store more than one file of ephemeris information for each satellite and prediction periods may overlap AN SMQ 11 Ephemeris Updates The AN SMQ 11 does not have the capability to interpret imported TBUS messages to update its ephemeris files Various parameters from the TBUS bulletin Part IV may be manually entered The SMQ 11 requires the epoch calendar date time group be entered vice the epoch decimal date time group NASA TWO LINE DATA Another predict message is the NASA Two Line Orbital Elements TLE bulletin This bulletin contains orbital information very similar to Part IV of
163. urn before the radar can switch into its receive mode Some portion of the return energy 15 lost and the radar may become confused and discard the pulse RADAR TRANSMITTER RANGE RESOLUTION A radar s resolution is its ability to display multiple targets clearly and separately Range resolution refers to targets oriented along the beam axis as viewed from the antenna s position Longer pulses have poorer range resolution Targets too close together lose definition and become blurred They must be more than one half pulse length apart or they will occupy the pulse simultaneously and appear as a single target The problem of range resolution will be discussed in more detail later PULSE REPETITION FREQUENCY PRF PRF is the rate at which pulses are transmitted per second It controls a radar s maximum effective range by dictating the duration of its listening time Increased PRF speeds the rate at which targets are repeatedly radiated This increased sampling results in greater target detail but the maximum range of the radar is reduced because of the shorter periods between pulses The WSR 88D can emit anywhere from 318 to 1304 pulses per second It has a maximum range of approximately 250 nautical miles nmi Listening Time Following the transmission of each pulse the radar switches to receive mode awaiting its return This break in transmission 1s appropriately called listening time When pulses do not return during thei
164. user commands such as zooming roaming displaying maps or overlays and implementing time lapse loops of products It also lets you annotate write or draw on products to highlight features such as fronts The processor also executes special product requests and 2 28 forwards them to the RPG The PUP processor is housed in a cabinet much like the RPG but its other components resemble a computer workstation e A system console alphanumeric terminal that is usually located in close proximity to the PUP work space It consists of a monochrome monitor and keyboard The system console controls the processor by invoking hardware and software commands that affect PUP functions It also receives alphanumeric products or messages that are not displayed on the graphic monitors UNIT CONTROL POSITION UCP The UCP is the fourth major component required to complete a WSR 88D system Because of its function the UCP is regarded as the radar s central nervous system fig 2 30 It ensures system integrity and reliability by monitoring and regulating each component s activities It is used to set all adjustable parameters that determine PRF antenna position and all processing thresholds The UCP is tasked with resolving operational conflicts such as load control when overload conditions occur The UCP executes commands via a narrowband link with the RPG 2 25 It manages both an application function and a system console function T
165. val Occupational Safety and Health NAVOSH Program Manual for Forces Afloat and OPNAVINST 5100 23 series VAVOSH Program Manual provide safety and occupational health information The safety precautions are for your protection and to protect equipment During equipment operation and preventive or corrective maintenance the procedures may call for personal protective equipment PPE such as goggles gloves safety shoes hard hats hearing protection and respirators When specified your use of PPE is mandatory You must select PPE appropriate for the job since the equipment is manufactured and approved for different levels of protection If the procedure does not specify the PPE and you aren t sure ask your safety officer Most machinery spaces and tools requiring you to wear hearing protection are posted with hazardous noise signs or labels Eye hazardous areas requiring you to wear goggles or safety glasses also posted In areas where corrosive chemicals are mixed or used an emergency eyewash station must be installed lubricating agents oil cleaning material and chemicals used in maintenance and repair are hazardous materials Examples of hazardous materials are gasoline coal distillates and asphalt Gasoline contains a small amount of lead and other toxic compounds Ingestion of gasoline can cause lead poisoning Coal distillates such as benzene or naphthalene in benzol are suspected carcinogens Avoid all skin con
166. ve either direct readout imagery or GOES WEFAX broadcasts The aiming operation is performed automatically by the system provided the ephemeris data has been entered properly for each polar orbiting satellite and the position data has been updated for the geostationary Satellites IMOSS SATELLITE MODULE The Interim Mobile Oceanography Support System IMOSS is a combination of three ELECTRONIC CABINET S CY 8838 SMQ 11 1217AS303 POWER DISTRIBUTION H CONTROL ASSY C 12539 SMQ 11 3511AS700 PRINTER ASSEMBLY PT 566 SMQ 11 3511AS800 UNINTERRUPTIBLE POWER J SUPPLY ASSY 8467 5 11 3311 600 124 Data Security Equipment KG 44 TSEC Electronic Cabinet CY 8838 5MQ 11 H Power Distribution Control Assembly C 12539 5MQ 11 I Printer Assembly PT 566 SMQ 11 J Uninterruptible Power Supply Assembly PP 8467 SMQ 11 Figure 1 24 AN SMQ 11 equipment cabinets Figure 1 25 AN SMQ 11 dual frequency array antenna subsystems the main subsystem the communications module subsystem COMM and the satellite module subsystem SAT MOD Each subsystem consists primarily of a laptop computer that can be used as a stand alone system depending upon mission requirements The main subsytem contains a multiple application software library dedicated to many aspects of METOC support The IMOSS comes equipped with a printer The SAT MOD consists of a laptop computer that conta
167. we will discuss some of the more commonly used derived products Composite Reflectivity CR Product Recall that base reflectivity provides a birds eye view of the radar coverage area While this is very useful base products provide data from only a single elevation angle Thus only a slice of the overall atmosphere 1 presented and valuable information above or below the radar beam may be overlooked To sample the entire volume scan radar operators must view each slice individually This time consuming process 15 impractical for the operational user The WSR 88D offers Composite Reflectivity CR as a partial solution The CR product contains information found in base reflectivity However one very important difference exists composite reflectivity operates on a summation principle That is the algorithm first compiles data from all elevations volumetric and then produces a product which displays only the strongest returns for all regions of the radar coverage area In building the CR product the algorithm considers only intensity as its criteria Size shape characteristic and altitude are not factored 2 40 The CR offers a sneak peek advantage over base reflectivity but should never replace the use of other reflectivity products When using CR operators are less likely to miss significant targets since only reflectivity maximas are displayed The major downside of this product 1s its loss of target heights T
168. wn CDA stations for the DMSP satellites WEFAX SERVICE Another method for receiving satellite imagery at your ship or station 1s to copy a WEFAX weather facsimile broadcast from a geostationary satellite WEFAX is the retransmission of low resolution infrared and visible satellite imagery from U S GOES satellites to any receiver capable of copying the signal WEFAX transmissions are also available via METEOSAT GMS and other foreign satellites The U S GOES WEFAX service provides visual and infrared sectors as well as full disk imagery The service also includes selected meteorological and oceanographic charts TBUS bulletins and operational messages You can check the NOAASIS web site for information on active WEFAX broadcasts broadcast content and frequencies Information concerning GOES schedules is also available via the Internet Detailed information on WEFAX services is provided in the WEFAX User s Guide issued by NOAA NESDIS Each GOES satellite provides high resolution imagery that is transmitted on a high frequency signal to CDAs and processed at NESDIS NEDSIS processes the signal to add gridding latitude longitude geographical boundaries borders for land and water masses and enhancement The CDAs then retransmit the processed signal back to the satellite for WEFAX transmission In turn the satellite retransmits the WEFAX signal back to earth on a lower frequency signal for reception by user operated satell
169. y beneath them at relatively high resolution Although nearly every environmental satellite provides both infrared and visual imagery polar orbiting satellites are better suited to gathering imagery from the high latitude and polar regions They also provide imagery as they cross the equatorial regions This makes them extremely well suited for oceanographic applications where slow changes in water temperature are adequately tracked by only two or four images a day The width of the usable image from a polar orbiting satellite 1s a function of the satellite s altitude The average swath width 1 about 2700 km 1500 nmi Characteristic Image frequency 15 minutes Poor Full disk Resolution at high latitudes Areal coverage Gnidding Data acquisition system cost Automatic Average life expectancy 5 6 years Table 1 1 Geostationary Versus Polar orbiting Characteristics Geostationary Very expensive Polar orbiting environmental satellite orbits are planned so that the usable image area overlaps slightly shows a typical TIROS N satellite while shows the area covered by usable imagery on successive orbits of a polar orbiting satellite As of this writing NOAA 12 TIROS ND and NOAA 14 TIROS NJ are the two fully operational polar orbiting satellites in the TIROS N series A new series of polar orbiting satellites will be launched by the spring of 1998 and will be
170. ystem Define radar sensitivity The acronym RADAR stands for RAdio Detection And Ranging Radio waves like light waves are reflected from objects The term reflectivity refers to the amount of energy returned from an object and 1 dependent on the size shape and composition of the AMPLITUDE AGM3F205 Figure 2 5 Amplitude of an electromagnetic wave object Through short bursts of radio EM energy weather radar equipment displays the location and intensity reflectivity of meteorological targets such as rain showers and thunderstorms is a block diagram for a simple radar system that consists of the following components e A modulator that tells the transmitter when to transmit and for what duration e A transmitter that generates power An antenna that concentrates the radiated power into a shaped beam which points in the desired direction and collects the echo signal for delivery to the receiver A duplexer that connects the transmitter to the antenna during the transmission of the radiated pulse and connects the receiver to the antenna during the time between radiated pulses e A receiver that amplifies the weak echo signals picked up by the antenna to a level sufficient to display them e A signal processor that evaluates the signal from the receiver e A visual display unit that presents the information contained in the echo signal to an operator for interpretation Of prime importance conce
171. ystems 1s the updating of ephemeris data Ephemeris data 1 information that describes the type orientation and shape of a particular satellite s orbit Ephemeris data 1 critical to satellite tracking as it provides key information that allows you to determine where a satellite will be located at any given moment This information 1 also used to allow the receiver system to predict where polar orbiting satellites will be at any moment in relation to the location of the receiver site More importantly ephemeris information enables your receiver system to earth locate the image that 15 to establish what area of the earth 1s depicted in an image received from a polar orbiting satellite Once an image has been earth located you can then merge appropriate geographical boundaries and a latitude longitude grid with 1mage Without accurate placement of a grid system even the clearest high resolution images are nothing more than interesting pictures Environmental applications require the analyst or forecaster to be able to determine where a feature 15 and how fast it is moving which is an impossible task without an accurate reference grid Since geostationary satellites do not move relative to the earth their ephemeris data does not need frequent updates However they are moved periodically and their positions are updated via special bulletins as necessary These bulletins are posted on the Internet at the NOAASIS web site Severa

NAVEDTRA 14271 Aerographers Mate Module 3 Environmental

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