Home

AHAS (AVHRR Hydrological Analysis System)

1. H 400 Sugarcane Taghmen 1987 ZEE RSEN Ca Pos Wright 1 964 85 65 Potatoes SS amp 80 gt Potatoes 18 wem SS L6 T 220 Meize Ice mud flats ERE Open water wet soil and sand o o SON oo p 0 001 0 005 05 0 5 03 5 1B 5 5n 05 05 gas HI D 01 2 05 10 188 y Maize crop 100 Airfield falowtamand 3 Orchard 3 30 ts 10 58 nefres 8 80 7 o3 30by t8 1 3 43 AHAS User Guide Biophysical Properties C swana 8 2 oos 94 48 swemns 35 2 w os os 74 savannah 23 3 34 12 91 958 ee oa o5 i5 20 2 40 1 Y Tiger bush 2 a o os 3 ___ SS RSR EE E C weya os o7 3185 oo oos o C Wmeada o9 09 25s 026 008 osm Vineyards 18 os 375 os os o Fractional Photosynthetically Active Radiation fPAR Photosynthetically active radiation PAR describes the solar radiation available for photosynthesis The fraction of solar radiation absorbed by chlorophyll pigments fPAR describes the energy related to carbon dioxide assimilation and is derived from PAR absorbed by canopy divided by the PAR available from solar radiation Acronym fpar Unit Range Min 0 max 1 precision 0 01 Create Fractional Photosynth Active Radiation
2. The system assigns a variable name T4 T5 e4 e5 AD1 and AD2 to these maps The user can use these names as shortcuts instead of the entire path of the files C45 C5 2 46 AVE C52 Dffsel 40 1 AVE AVE AVE EES DE E4 E5 The c constants are entered by the user The user can enter a simple equation four basic Methods to generate surface temperature Dp File Surface QUU operations as any linear combination of the all Customize Method y maps and constants or AUI The system also knows two more maps AVE and DE The user can use the shortcuts for these two names as well Displacement height d Acronym d Unit meter Range Min 0 max 30 precision 20 001 Displacement Height an X Input Images Wee fu Leaf Area Index Map Free Parameter cd Output File Dr CIA See also Surface roughness for momentum transport Displacement height input The basic map for the displacement height d is the vegetation height map bh that should be entered by the user The UI allows browsing to locate the map In the most extreme case of lack of data the UI allows to enter a fixed h value constant for the entire area in the h map box Instead of browsing just enter h in meters For more references to the height map see vegetation structure The user is also requested to select a different cd a default of 20 6 is given The vegetation height map m
3. Input Files Interpolation aolarmeter Station Map station a i Show Station Attribute T able station gt xd C Show Table Instantaneous Exo Shortiwave Solar Hadiation kexo Ca 7 C Instaneous Exo Shortwave Radiation Output File M Bk Close Show Histogram Eze T pu cum c o o ou o oro os mA BEE Instantaneous incoming shortwave radiation input There are two cases Case l There is no ground information on incoming SW radiation on the ground The user enters a uniform value of transmissivity for the entire area default 0 75 or selects an external transmissivity map Any situation can be handled from the same box The K1 map is calculated based on the equation Klar KI Case ll There are ground pyranometers available in stations in the area This map has to be evaluated from ground data measured in meteostations First class meteostation might have this value as a standard reading using solarimeters or pyranometers The final K4 map is an special interpolation from a point map e To access the dialog box for Case II click the station map button Required raster maps for cases and Il e Instantaneous terrestrial solar radiation The user can browse or create it from the dialog box For case Il It is also required a point map e Point station map with the meteostations and its attribute table a There are instantaneous measurements of incoming shortwave radiation data from pyranometers i
4. OF Cloze Show Histogram d OQ E MXIU A AA oD A ARA IO Fractional Photosynthetically Active Radiation input The procedure attempted in this interface follows the model explained by Asrar G Mynenei R B Choudhury B J 1992 where fPAR is related to NDVI It is strongly recommended to read the corresponding article to verify the applicability of the default gain and offset fpar offset gain NDVI where NDVI is the normalized vegetation index map Defaults Gain 1 2222 Offset 0 1914 both changeable by the user AHAS User Guide 44 Climatic Characteristics Climatic Characteristics Daily terrestrial solar radiation Klday 9 The horizontal integrated daily value of the terrestrial solar radiation over all wavelengths Acronym K1 Unit megajoules m day Range Min 0 max 70 precision 20 001 Solar zenith angle map omn zl ate fi 297399 B Close Show Histogram To select a solar zenith angle map Daily terrestrial solar radiation input Kday Since the user interface has a simple and accurate in built solar radiation model the only data required by the user is the date for the calculation The other data required position on Earth is read by the system from the lat long coordinates assigned to the image selected by the user the solar zenith angle map by default Average dai
5. applied to several images of the same region Then once the table is complete the user has the option to save the input vegetation structure data and load it in any occasion Any line a vegetation structure description can be selected for deletion by pressing the cell to thee right of the height column in the corresponding line The marker arrow activates and the line is selected To delete it press the delete button e Once a line is selected the scrolling arrows below the de input table could be used to go up and down Alternatively just select other column using the mouse AHAS User Guide 32 Biophysical Properties If anything goes wrong in the de calculator press the Refresh button to reset the calculator Data is not lost in the operation Options when de calculator is off The user does not use the in built calculator 1 The Would you like to apply the de calculator option must be unchecked 2 The user calculates the one unique overall de value that goes as input in the corresponding cell He decides then the procedure to weight the value 3 The user enters one overall emissivity value for a fully vegetated pixel and one for the fully bare soil pixel 4 The user need to enter the Pv Vegetation proportion map 5 Select a name for the output map and press Ob Surface temperature To It is the skin temperature of the land surface i e the kinematic temperature of the soil plus the
6. g a e w ben a ben Accumulated Biomass Bact Biomass is living or recently living plant or animal matter lt can also refer to any particular part of a plant or organism as well Defined as energy the biomass resource can be considered as organic matter in which the energy of sunlight is stored in chemical bonds When the bonds between adjacent carbon hydrogen and oxygen molecules are broken by digestion combustion or decomposition these substances release stored energy This is an AHAS M product Acronym Bact Unit kg m Range Min 0 max 300 precision 0 01 Select a project File L Apr Load a file to list ime series of input images Its car bsp lmage SE T 3test3 hpr Pei zr Absorbed Fhotosynthetical Active Radiation M aps Lists of Time Series of Images ESHBSPMMABESSET 3 Sapar ET Project CNRBSPSIMAGESSET 3 Saparz a Acquision mme ddzuy CA DDCDIkIATZESCDT oO rd Evaporative Fraction of the surface Energy Remove Ferad 5ec XRHbsp lmagessE T 3serl E B ETUR W Crop map el Save Crop conversion Factars EEF 2 5 v c3 crap Load E Iv cd crop Specify the output file Accumulated Biomass input The user is warned about the impossibility to account for different crop types using this methodology Two generic crop types are the maximum the system can handle Inputs are 1 A raster map called mask identifying c4 and c crops The other pixels
7. 0 53 0 53 0 53 37 Create Surface Temperature Input Files f mnrl T4 Brightness Temperature for Channel 4 Channel4 T5 Brightness Temperature for Channel 5 Biophysical Properties Channels em C52 0 Offset 3218 2218 0 858 Methods to generate surface temperature Output File Surface Temperature JOttle and Vidal M adjar 1932 k Show Channel 4 C Channel5 OK Show Histogram K offset 0 858 0 854 0 833 0 852 0 88 0 924 0 928 0 91 0 929 0 403 0 418 1 687 1 761 2 889 3 151 0 502 0 515 2 186 2 239 1 301 1 368 AHAS User Guide Biophysical Properties Ulivieri el al 1992 Cano 0 C 2 8 Cas 0 Cs 1 8 Lo 0 Offset 48 1 2 75 Ae Required maps Emissivity in channel 4 and 5 Required procedure Calculate AVE and DE maps by pressing the correspondent buttons before the final calculations University of Valencia 1995 Ce 0 58 Ge 2 Ae 0 1 w 1 118 Cas 1 16 esl Caen 0 58 Offset 40 51 40 e 68 w 163 Ae Where W a value that represents the total water vapor column in the atmospheric profile gr cm usually between 0 to 6 Required maps Emissivity in channel 4 and 5 Required procedure Calculate AVE and DE maps by pressing the correspondent buttons before the final calculations AHAS User Guide 38 Create Surface Temper
8. _ CH2SUR CHISUR CH2SUR CHISUR Where e NDVI and the NDVI are the NDVI values of the user selected for pure ground and pure vegetation pixels The user has to enter the NDVI and the NDVI values e NDVI is the NDVI map e K is the ratio between the difference of the reflectance of the fully vegetated pixel in Channel 2 and Channel 1 by the same difference but for the bare soil pixel It is an image constant e CH1SUR and CH2SUR are atmospherically corrected reflectance e P is the vegetation proportion map Considerations e NDVI and the NDVI are image constant values that might correspond to the minimum no water and maximum NDVI in the reference image Vegetation proportion map This map must is not the fractional vegetation map as was built in the biophysical properties menu in the Ul In order to built the map the user might press the input independency launcher button e Before solving this map the user must be acquainted with the theory e he operation triggers a procedure were the system searches for the highest and the lowest NDVI pixel in the image For these pixels the atmospherically corrected reflectances in channel 1 and 2 are place in the dialog box e he user can display the histograms and maps in order to verify correct the input data If the user wishes to change the default selected values he must enter the new column and row for the pure vegetated and or bare soil pixel and press enter to a
9. sq A VE C52 0 Dffset 1 274 E4 Emissivity map in channel 4 ES Emissivity map in channel 5 PO Methods to generate surface temperature Output File Surface Temperature Becker and Li 1990 v Show ES Channel 4 C Channel 5 OK Close Show Histogram 9 Create Surface Temperature x Input Files mon T4 Brightness Temperature for Channel 4 channels T5 Brightness Temperature for Channel 5 channel5 GG Coefficients Used to Generate Surface Temperature Map C42 0 C4 a E4 C45 0 C5 b E5 amp 246 C52 0 b 2 46 Offset 40 1 E4 7E 44273 15 1 C4 C5 Ta Ed Emissivity map in channel 4 Eo4 g ES Emissivity map in channel 5 feo5 gl KE Methods to generate surface temperature Output File Surface Temperature Prata and Platt 1991 t Sho SE Ce Channel 4 C Channel 5 DK Close Show Histogram 9 AHAS User Guide Biophysical Properties Vidal 1991 Cao 0 Create Surface Temperature X Input Files f morl Gm T4 Brightness Temperature for Channel 4 emm um 45 Cs 9 78 T5 Brightness Temperature for Channel 5 Channels um C 5 2 0 Coefficients Used to T Bion a Na C Offset 50 1 2 e 300 e e amp C42 AVEsE4 ESU2 Required maps ip DE e slEA ES Emissivity in channel 4 and 5 o C52 0 Required procedure Offset 50 1 AVE AVE 300 DE AVE Calculate AVE and DE maps by pressing the E4 Em
10. T Display the histogram of the map Photosynthetical Active Radiation input The map required for this output is created in the user interface The required input can be browsed or created from this create dialog box Inputs are e Average daily incoming shortwave radiation Kday e The user has to decide a value for c default 0 48 Absorbed Photosynthetical Active Radiation APAR It is the fraction of the PAR absorbed by the canopy and used for carbon dioxide assimilation APAR PAR PAR where e PAR is the Photosynthetical Active Radiation e fPAR is the Fractional Photosynthetically Active Radiation Acronym APAR Unit watt m Range Min 0 max 1000 precision 20 01 71 AHAS User Guide Agro ecological indicators Absorbed Photosynthetical Active H adiati n XxX Input Files Output File gt e OF Close Show Histagram T uM ud cu a Ci E Display map Absorbed Photosynthetical Active Radiation input The map required for this output is created in the user interface They can be browsed or created from this create dialog box Inputs are Fractional Photosynthetically Active Radiation fPAR Photosynthetical Active Radiation PAR AHAS M Some outputs of the Agro ecological and Planning indicator levels require multi temporal analysis capabilities AHAS interface is essentially project based meaning treatment for one image only A project for AHAS is equivalent to prod
11. The soil heat flux in the dry pixel Gar watt m e The surface roughness for momentum transport Zp ary m e The first estimate of the friction velocity U 9 ary m s e The first estimate of the aerodynamic resistance to heat transport fano ary sec meter b Evaluation of the linear regression coefficients for surface air temperature relationship The process assumes a linear relation between the surface air temperature with surface temperature Two coefficients a offset and b slope are evaluated and stored by the system 61 AHAS User Guide Climatic Characteristics AT Any O E b where AT Mo Ga Tuna st an dll To ary epum Pa C a S bi lg where pa is taken from the moist air density map kg m Gd is the air specific heat at constant pressure Joules kg K c Evaluation of the first AT map This map difference between surface and air temperature is calculated as ATa a b T where T is the surface temperature map K d First estimate of the sensible heat flux It is done for neutral conditions H if ATa 0 p c ATa r 0 1 e The result is then input for the first iteration procedure Calculating step wise the first estimates of the Monin Obhukhov stability length Lmo m see momentum flux theory 3 P Ce Ux edy E is 4 022 H f Characteristic length scale for momentum Xm inverse of the buoyancy effect correction for uns
12. a file to list time seres of input images ltz E Lists of Time Series of Images Comments Specihi the cutout file Create Close 7 PO Accumulated APAR input A single AHAS project covers a certain portion of space the same in this case at a certain time A single AHAS M project integrates in time several AHAS projects having the same spatial coverage See AHAS M For the creation of ACAPAR images APAR input images from several AHAS projects are required The AHAS M user interface allows the user e Browse the system for APAR images belonging to different projects e Add Remove these images to from the final ACAPAR calculations e Add the time frame seconds for each image The time frame is the time of Photosynthetical accumulation valid for each image e Save and load the selected set of multitemporal APAR images in a file The user can retrieve them again without re selecting Required inputs e APAR images in the current or other AHAS project Browsing for APAR images is possible Double clicking displays the image e The addition of the time frame valid for each APAR image seconds Enter using keyboard Commonly time frames will depends on the time frequency of images available 73 AHAS User Guide JS Tr 1 1 Agro ecological indicators Images and time frames T1 Ts T3 T4 T5 TG i TS AJA AAA 788 3 L BM RSR NND ben z ben c ben p aew G a e w
13. are undefined The user should verify the interpolation method The moving average inverse will seems the most appropriate to smooth out differences The calculations are performed after selecting a proper name for the output map and pressing the button OK Instantaneous terrestrial solar radiation It is the total solar radiation that reaches the top of the atmosphere at a certain moment in a predefined horizontal position on Earth Solar radiation is usually call visible range 0 3 um Acronym K Unit watt m Range Min 1400 max 1400 precision 0 1 47 AHAS User Guide Climatic Characteristics Solar zenith angle map solzer gt Date mm dd yy 229399 Output DE Close Show Histogram T Instantaneous terrestrial solar radiation input Since the user interface has a simple and accurate in built solar radiation model the only data required to be entered by the user is the date for the calculation The other data required is e Position on Earth coordinate of the pixels is read by the system from the lat long coordinates assigned to the image selected by the user the solar zenith angle map by default e Position of the Sun solar zenith angle is read by the corresponding file created during the preprocessing of the AVHRR imagery Daytime duration This map shows the total duration of the daytime sunrise to sunset at any location The map indicates then the total sunshine hours
14. box map windows and tables are closed e After one image has been created in via AHAS it will be stored in the working directory ILWIS treats this image as any other so the user can apply all ILWIS functions over the created image e Absolute maximum amount of characters allowed in an output map table or point map is 8 but a maximum of 7 is recommended e n order to reduce the amount of undefined pixels in many outputs be certain that the image is cloud free the atmosphere is clean no smokes and all radiometric anomalies have been masked fires high reflective bodies sunglint e After the installation a file named AHAS ini is installed in your Windows directory where paths for running ILWIS2 2 and AHAS exe are defined By default the application will be installed in c program files ahas 13 AHAS User Guide Spectral Composites Spectral Composites Color Composite Images Combining 3 raster images bands maps creates a color composite One band is displayed in shades of red one in shades of green and one in shades of blue Create Color Composite E X GG Use Linear Stretching MV Use the Intervals as Min Max Use Histogram Equalization Cancel The Intervals of Input Values LL Red Band RN be Histogram Green Band SN 5 Show Blue Band SN Eeer Py SEA RAE E A A A RN TESTED Hed channel S BUI C Green channel2 ux f Blue channel Gil Dutput Map Assign channel
15. but instantaneous air temperature and relative humidity e The user is requested to enter the value of the relative humidity RH i 9e and air temperature at screen level Ta i C at the moment the image was taken in the station e For stations without these data enter the undefined character in the corresponding columns e The user must verify the interpolation method prior to final calculations lt is advisable the moving average inverse for this case e he Lin is calculated in the stations in a temporal column in the attribute table A point map is created out of this column C The user close the table gives a name for the output map and click OK Instantaneous incoming shortwave radiation KL It is the horizontal solar radiation that reaches the ground at a certain instant in a certain Earth location Solar radiation is usually call visible range 0 3 um Acronym KJ Unit watt m Range Min 0 max 1200 precision 0 1 Transmissivity constant Create Instantaneous Incoming Shortwave Solar Radiation x Input Files Station Map Transmissivitu 0 75 Pm Show Transmissivity Map Instantaneous Exo Shortwave Solar Aadiation Output File OF Close Show Histogram Y Transmissivity calculated from stations accessed by pressing button station map AHAS User Guide 52 Climatic Characteristics Create Instantaneous Incoming Sh ilwave Solar Radiation XxX
16. canopy surface or in the absence of vegetation the temperature of the soil surface The surface temperature retrieved from NOAA mostly uses a linear combination of the thermal channels and the different emissivity in both channel to produce an atmospherically corrected thermal image The procedure is called Split Window Technique There are several approaches for SWT some of them are treated in this software The general equation for the split window technique for a 2 thermal channel can be written as Te CHABT te CHABT Ae CH ART CH5BT c CHSBT c CHSBT offset where T Is the surface temperature in Kelvin CH4BT and CH5BT are the brightness temperature maps for channel 4 and 5 in Kelvin Acronym To Unit Kelvin Range Min 250 max 350 precision 0 01 Procedure available in the Ul SST no emissivity Coll and Caselles 1997 Price 1984 Becker and Li 1990 Prata and Platt 1991 Vidal 1991 Kerr et al 1992 Ottle and Vidal Madjar 1992 Ulivieri el al 1992 University of Valencia 1995 Coll and Caselles 1997 Customized method Surface temperature input The user interface provides several well known methods to calculate Land Surface Temperature LST Most of the land surface temperature SWT require emissivity maps for channels 4 and 5 4 5 Other methods need the percentage of vegetation P Others assume image constant values for the image like total water vapor column w gr
17. follows and iteration procedure that to adjust of all these variables Acronym H Unit watt m Range Min 1000 max 1000 precision 20 1 Acronym u Unit m sec Range Min 0 max 10 precision 20 01 Acronym zah Unit sec m Range Min 0 max 1000 precision 20 01 57 AHAS User Guide Climatic Characteristics Create Sensible Heat Flux Input Images mpr Surface Temperature Map TO Instantaneous Met Radiation M ap Instantaneous Soil Heat Flux Map Surface Roughness Map Displacement Height Hap m eiss Ar Lar 8 n alza zu mz 7 eiss Pixel Values on TU Input Point Date Station M ap Im Driest 352 6 Attribute T able ate E 7 wettest 277 8 EE of the ee a a oli 282 How ry 24 L alw er h Fro et 137 o en Blending Height rn 100 Sensible Heat Flux Sir Specific Heat 004 16 Resistance to Heat Height at Uz m UU Friction velocity Height Reterencelm 5 Wind Speed Uz Ir Show D phone E EEN Ge Surface Temperature Net Radiation C Soil Heat Flux C Surface Roughness tC Displacement Height Station Map Attribute Table See Help file for the Momentum flux calculator spread sheet Momentum flux implementation The sensible heat flux solution is an implicit system of equations that requires iteration The aerodynamic roug
18. has to enter the best possible data closest to the moment the satellite passed over the station In the create instantaneous longwave radiation menu the user has to browse or create the point station map with the meteostations and its attribute table Procedure a The user creates opens the meteorological station point map having the same georeference as the other maps This is done from the dialog box create instantaneous incoming shortwave solar radiation Select show station show button In case a new station has to be added initiate point editor add the station a name for it and press enter to confirm See also point map editor b The meteorological station point map is linked to a table containing meteorological data 51 AHAS User Guide Climatic Characteristics where the user enters attributes meteo data of different kind for each station The user is able to edit the meteodata point map and add remove meteostations at any moment See IL WIS help file ILWIS point maps e he user opens the attribute table by pressing column table button in the create menu or by selecting show table and press show button e The attribute table opens Then there are 2 options Option 1 the user has information on direct measurements of longwave incoming radiation at the station from appropriate instruments e The user enters the instantaneous value for the station in the column Lin i Option 2 There are no radiometers at the stations
19. initially 11 ILWIS maps to operate These images must be created outside of this user interface using a specialized AVHRR pre processing package 1 Reflectance maps in channel 1 and 2 CH1 amp CH2 non atmospherically corrected e Units reflectance min 0 max 1 precision 0 001 2 bytes 2 Reflectance maps in channel 1 and 2 CH1 amp CH2 atmospherically corrected e Units reflectance min 0 max 1 precision 0 001 2 bytes 3 Brightness temperature for channels 3 4 and 5 e Units Kelvin degrees min 250 max 350 precision 0 1 1 byte for Channel 4 and 5 e Channel 3 might have higher ranges e For these paper these maps are called CH3BT CH4BT and CH5BT 4 Solar zenith angle map e Units degrees min 0 max 90 precision 0 1 1 bytes 5 Satellite zenith angle map e Units degrees min 0 max 90 precision 0 1 1 byte e For this paper this map is called VZA 6 Solar azimuth angle map e Units degrees min 0 max 360 precision 0 1 2 bytes 7 Satellite azimuth angle map e Units degrees min 0 max 360 precision 0 1 2 bytes Total 11 raster maps e n order to reduce the amount of undefined pixels in many outputs be certain that the initial images are cloud free or cloud masked the atmosphere is clean no smokes and all radiometric anomalies have been masked fires high reflective bodies sun glint To mask an image set as undefined the anomaly pixels See ILWIS help file ILWIS undefined e All maps must have a unique coordinate
20. map Reflectance channel 1 with Reflectance channel 2 with al he Ul filters the file list to shown only False colour composites he file types selected by the user and False colour composites available if any in the project Normalize difference vegetati Soll adjusted vegetation index Say L SHBSPIMABENSSET3 Fractional Vegetation Cover vc L SRBSP IMABGESSET3 Leaf Area Index lai L SRBSP IMAGESSET3 x b Show Map window ae Thematic menus Spectral composites 3 submenus Biophysical properties 13 submenus Climatic characteristics 15 submenus Water characteristics 4 submenus Agro ecological 4 submenus Planing allocation indicator under construction The file list indicates all file types file names and file location in the current AHAS project File management After selecting a file in the file list the user can e Display the map by pressing the show map button e Display the histogram by pressing the Histogram button e Delete the file from the project It will not remove from the HD by pressing the Delete button This function also accepts multi file selection Display all files in the project by pressing the display all button Create outputs From the thematic oriented menus the user selects an specific output Then all outputs of the same type available in the project if any display on the file list The others hide press display all to see all outputs To create a new output of the selected type
21. map where the Ul automatically creates all relevant columns needed for the user to enter Kay data by pressing the button column table button 3 Create or identify maps needed for the calculations if periheliometer data is needed e Sunshine fraction map e Terrestrial daily solar radiation map These two maps can be created from this menu or browse in the system The UI assigns default maps already existing in the UI Attribute table data input The attribute table opens by selecting the Show table option and pressing the button Show There are three possible cases e Case I The station has daily solarimeter data The user only enters the average daily solar radiation in the corresponding column Kin da for these stations care it is watt m and not Megajoules m day If these stations have periheliometer data the user might enter this data type as in case ll but for this calculations this data is ignored e Case ll The station has only periheliometer hours of sunshine data The user enters a The constant as and bs for the corresponding stations default as 0 25 and bs 0 5 in the respective columns b The hours of sunshine in this day in column Sun hs d c The Kin da column stays undefined e Case lll The station does not have information related to this variable a The user does not enter any information in this case b The user checks that the values of the columns Kin da as and bs
22. o Dad 46 DAYTIME DURA TION dotati iaa 48 EE eege 46 SUNSHINE FRAC TION CO si possisipsc to tars os oa Roe let eebe 48 SIGISHLHE TRACTION TPUT Ee AS Geass aote AAA dene E een tr ede eaa tee 49 AVERAGE DAILY NET LONGWAVE RADIATION UDAY enne eren nennen ns 49 Average daily net longwave radiation input ooccccccccnonnnnnnnnnnnnnnnnnnanonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnanannnnnnnnns 50 INSTANTANEOUS INCOMING LONGWAVE RADIATION n 5 Instantaneous incoming longwave radiation input oocccccnccnnnonncnnnnnnnnnnananonnnnnnnonannnnnnnnnnnnannnnnnnnnnnnnaninos 51 INSTANTANEOUS INCOMING SHORTWAVE RADIATION Kl 32 LEDS MESSI COR STAN NA A A Sois 52 Instantaneous incoming shortwave radiation mp 53 INSTANTANEOUS OUTGOING LONGWAVE RADIATION LT mer pm 54 Instantaneous outgoing longwave radiation I0puf nnne sse 54 INSTANTANEOUS NET RADIATION RN EE 54 Instantaneous Het TOGIGUON Eege eelere 55 OMG HEA ET E EE Ci Pc 55 SOLU heat Hee A AA A AAA Ada 56 TOTAL DATE INE RADIATION ee EE EE S6 Total day NCL TALANI TAPIA i eege 57 SENSIBLE HEAT H FRICTION VELOCITY U RESISTANCE TO HEAT Za eere 57 Momentum Tu IP METANO SS AAA eins 56 MOMENT FON PUT AAA SA ASAS 64 WATER CHARACTER US PIGS eege 66 POTENTIATE VY APOTRANSPIRATION PE P A usura ii ti ted editora tede 66 Potential evapo rans Pirati On IPUR 66 INSTANTANEOUS TOTAL WA TERUSE L ade na A A AA Tta 67 Instantaneous total Water use EE 66 EVAPORATIVE ERAC PON eeb
23. project window Alternatively select the image an press show map in the project window or simply double click the map in the project window Information on the functionalities of a map window in ILWIS e Histogram display the histogram of the image selected in the project window Alternatively select the image and press histogram in the project window AHAS User Guide 10 Introduction to AHAS e Image properties Selecting any image in the project window and then by applying this function the system displays full information of the image attributes like coordinate system georeference pixel and image sizes This information is relevant when importing or adding ILWIS maps into the project e Pixel info Pixel info allows you to interactively inspect values in one or more raster maps Once this option is invoked a collection box appears First open one any AHAS map preferably one if user interest Open the pixel info box he user could pick one by one images from the project window drag and drop them in the pixel info box By clicking on any specific pixel in the map the pixel value and amount of pixels with the same value is transferred and displayed for all maps listed in the pixel info box Tools e Run llwis launch the ILWIS software in case the user closes it by mistake e ILWIS map calculation This option launches ILWIS map calculation functions The user can directly make use of ILWIS map calculation functions t
24. stations have periheliometers measuring hours of sunshine First class stations might also have periheliometers Then the final map is a special interpolation from a point map containing e Kl data from first class station entered by the user e Ki gay data calculated from sunshine hour s data using a simple model derived for meteorology purposes e Other stations might exist but do not add information to obtain the final map The following equation relates hours of sunshine and daily radiation n exo K EECH Tb E ei where Kl the daily terrestrial solar radiation megajoules m day n N is the sunshine fraction a and b are constants to be evaluated at ground stations a b total fraction of terrestrial radiation reaching the ground in a complete clear day a is the fraction of terrestrial radiation reaching the ground in a complete overcast day a and b have to be calculated at any station Default values a 0 25 b 0 5 Kl the daily average ground solar radiation watt m3 If one station has both solarimeter and periheliometer data the calculation for the station is performed with the solarimeter data ignoring the rest AHAS User Guide 46 Climatic Characteristics Procedure Basically the user needs 1 To create or open a point station map where the user is able to position the station on the map and add a name or identification 2 To create or open an attribute table for the point
25. structure map is available select Vegetation structure map in the Option on method sector Once emissivity data for cases 1 to 4 are solved the final narrow band map calculates by pressing the OK button Cases 1 or 2 For cases 1 or 2 the first choice is to use the in built de calculator or not 1 Theuser requires the use of the de calculator de 1 2eg amp F I Pt Ps 0 8 6 G 1 amp amp F Ps AHAS User Guide 28 Biophysical Properties 24 Narrow band emissivity Py Vegetation proportion T de gt emissivity value e Would vou like to apply de calculator Height m Spacingimi Breadth m BE WEI Enter the structure information then click Apply botton to calulate lt de gt value Pe FE Delete Refresh Load Save Apply Option oni method Option on lt de gt calculator LIU Ma vegetation structure map e Average de emissivity value C Vegetation structure map Weighted de mean value Specify the output OF Close Show Histagram Database P 1 It is the option by default The Would you like to apply the de calculator option must be checked 2 f the user is in case 1 then select Average de emissivity value in the Option on lt de gt calculator The weight column must be kept empty 3 If the user is in case 2 then select Weighted de mean value in the Option on lt de gt c
26. the project opens all the components contained in the project will be listed in the project window which enable you to add create and explore the geographic information Important information e ILWIS works independently from AHAS so you might use it at the same time but never when AHAS is performing a calculation In this case be sure that all ILWIS pixel Info box map windows and tables are closed After one image has been created in via AHAS it will be stored in the working directory ILWIS treats this image as any other so the user can apply all ILWIS functions over the created image 9 AHAS User Guide Introduction to AHAS AHAS environment AHAS main application window Es AVHRR Hydrological Information 5ystem rie Project iew Tools Help w KIK From File menu select Open Project to load contents of project File 14 13 24 11 33 The main application window contains the tools for e Project management e Image analysis e Point interpolation File Menu New project when working in a project select this option to initializes a new one Open Project opens an existing project Close Project closes the working project Save project saves the working project Exit exits AHAS The most recently used AHAS projects will display at the botton of this menu The user can access the project by just clicking on them Project Menu e Properties AHAS is mainly a project based software one image one site
27. water needed to meet the water loss through evapotranspiration of a disease free crop growing in large fields under non restricting soil conditions including soil water and fertility and achieving full production potential under the given environment The Priestley and Taylor method is used in this Ul to evaluate the Potential evapotranspiration Acronym PET24 Unit mm Range Min 0 max 50 precision 0 1 Create Daily Total Potential Evapotranspiration X Input files Interpolation snanmeter Station Map station ce rd Show Station Attribute T able station GG 14 Show Table Total daily niet radiation E 2 C Show Priestlep Taplor coefficient cp the specific heat of moist air 1 26 1004 16 Output File IT OF Close Show Histogram Esel T Potential evapotranspiration input Input maps All maps required for this output are created in the user interface The required input can be browse or created from this create dialog box e Total daily net radiation Rnday Coefficients to be change or confirmed Cp Specific heat of air at constant pressure Default 1004 16 J kg KI Priestley and Taylor coefficient Default 1 26 Point data input Some meteorological data for the station is required for the calculations Many of them were already entered Procedure a The user creates opens the meteorological station point map having the same georeference as the other maps This is don
28. x axis and read o and B in the ordinates Required maps Emissivity in channel 4 and 5 Required procedure Calculate AVE and DE maps by pressing the correspondent buttons before the final calculations Biophysical Properties Create Surface Temperature x Input Files morl T4 Brightness Temperature for Channel 4 Channel T5 Brightness Temperature for Channel 5 Channels Gel C42 0 33 AVE E4 E51 2 C4 2 34 DE E4 ES C45 0 78 C5 1 34 fao C52 0 38 b EN Offsete0 56 a 1 5VEb DE E4 Emissivity map in channel 4 ES Emissivity map in channel 5 Methods to generate surface temperature Output File Surface Temperature Col and Caselles 1997 y r Show Ge Channel 4 C Channel 5 a OK Close Show Histogram R Alpha and Beta Caselles and Coll 1997 alpha a beta 2 water vapor gr cm 1 39 AHAS User Guide Biophysical Properties Customized method Create Surface Temperature xj Input Files f morl It is an attempt to customize all possible cases of De Split windows that might occur for NOAA e Chernels m 2 AVHRR T Chans g S Ga The user should be able to browse and locate e Channel 4 and 5 T4 and T5 p N o m e emissivity maps 4 and 5 E4 and E5 Coetticient Definition 00 e two possible additional maps AD1 and AD2 uz fT BEEN mmm
29. 0 41 u T n2 I After which the new sensible heat flux may be determined after obtaining constants a and D and ATas H iflATa 0 p c ATa Ir 0 1 The iteration continue till no more changes are detected in the H map At the end of the process 4 maps are available for the system They are calculated during this process and can only be available at the end of the calculations The maps are e Sensible heat flux H e Aerodynamic resistance to heat transport Fan e Friction velocity u e Wind speed u at any height based on the formulas 63 AHAS User Guide Climatic Characteristics MO H d u gt h er 0 41 i See Help file for the Momentum flux calculator spread sheet References e Bastiaanssen W 1995 Regionalization of surface flux densities and moisture indicators in composite terrain A remote sensing approach under clear skies in Mediterranean climates Doctoral Thesis Landbouwuniversiteit Wageningen The Netherlands Momentum flux input Input maps All maps required for this output are created in the user interface The required input can be browse or created from this create dialog box Surface temperature map Instantaneous net radiation map Instantaneous soil heat flux map Surface roughness map Displacement height map Point data input Some meteorological data for the station is required for the calculations Many of them were already entered e Click
30. 56 59 Solar zenith angle 7 11 78 79 Sorting keys 79 Specific heat of air at constant pressure Cp 66 Status help area 82 Sunshine fraction 47 48 49 50 Surface roughness momentum zo 40 41 59 T Transmissivity 53 Transmittance 22 Transpiration coefficient tc 20 21 87 Agro ecological indicators V Value scale 81 Vegetation structure 28 Volumetric soil water content 0 69 W Wind speed 59 63 AHAS User Guide
31. AHVRR Hydrological Analysis System User Manual Version 1 3 os WRES EEC 2000 rr Fe WRES ITC 2002 by Ir Gabriel Parodi AHAS User Guide AHAS User Guide Credits and acknowledgments This software compiles more than 60 different methodologies developed by hundreds of authors Without their intensive and costly efforts this product would never be possible We owe this package to all of them We are indebted to the ILWIS development team for their cooperation during the programming period Staff Overall algorithm documentation and recommendations MSc Ir Gabriel N Parodi and Prof Dr Wim G M Bastiaanssen Software project coordination MSc Ir Gabriel N Parodi Algorithm compilation programming documents MSc Ir Gabriel N Parodi IL WIS linkage software design and implementation MSc Lichun Wang Help file compilation design and writing MSc Ir Gabriel N Parodi Software testing MSc Lichun Wang MSc Ir Gabriel N Parodi and Dr Ir Ambro Gieske All of them staff from WRES Division International Institute for Aerospace Survey and Earth Sciences ITC P O Box 7500 AA Enschede The Netherlands December 1999 AHAS User Guide Table of Contents CREDITS AND ACKNOWLEDGMIEN DIS das esses ice sce duco dude 3 STAPE e I EN 3 INTRODUCTION TO AHA Sound ces veut aet ea ede o secu Alda Aide e eae do Ada 7 INTA MAPS RE 7 HARDWARE SOFTWARE REQUIREMENTS a 7 E EE 7 INS TA CEA EE 8 Ee E S
32. BAND SURFACE ALBEDO RO 22 2 Ways transmittaunce EE 22 Transmittance from stations opened from the constant method eese 22 Broadband suabcexitbedo UID Uu ee 27 THERMAL INFRARED BROADBAND EMISSIVITY EU 24 Thermal infrared broadband emissivity mp 24 NARROW BAND E RE 24 EE 25 Vesetunon DrODOFUOn JHa1 ascscsscdhee ee e aree A esae ee ea breed taa ee 25 Vegetation proporiton Jap ANNU ss ssi piv rie A RERO EVE FRREC RA COL OR YER UIN Y GERE dV UN Rods 26 e 2 i PR 26 PV VESCIGUON DEOPOTR OMA uranio ear Pete bte a DP ia 26 Sade Clo Tatort SPI EE 32 OESR C U AA A II TUN 32 Options when de caleulatof E 33 AHAS User Guide SURFACE TEMPERATURE LOL desee eoo das A ee CE biet Mato tao pru de d See 33 SUT ACC tempe rdir e PUN n dadas 33 DISPLACEMENT O in 40 Displacement EE 40 SURFACE ROUGHNESS FOR MOMENTUM TRANSPORT G A 4 SUICIDA idas 4 FRACTIONAL PHOTOSYNTHETICALLY ACTIVE RADIATION PDBART enne nnn 44 Fractional Photosynthetically Active Radiation input eee 44 CLIMATIC CHARACTERISTICS E 45 DAILY TERRESTRIAL SOLAR RADIATION Kip oo T RT 45 Daily terrestrial solar radiation input kd 45 AVERAGE DAILY INCOMING SHORTWAVE RADIATION KU pay eene 45 Average daily incoming shortwave radiation Inf 46 INSTANTANEOUS TERRESTRIAL SOLAR RADIATION eee e nenne eene mene nese ese sese ese ines n insi nn is 47 Instantancous terrestrial solar radiation IWDUL is AE va pA SR PER A REA UN
33. DVI CH 2SUR CHISUR Where CH1SURand CH2SUR are the atmospherically corrected ground reflectances in channel 1 and 2 expressed in decimals Acronym ndvi Unit Range Min 1 max 1 precision 20 01 Normalize difference vegetation index Dh ee la Show Near Infrared Ce Show Red OF Close Show Histogram i Soil adjusted vegetation index SAVI 1 L CH2SUR CHASUR CH2SUR CHISUR L SAVI Where e L is a non dimensional correction factor which ranges from O for very high vegetation cover to 1 for very low vegetation cover The most typically used value is 0 5 which is for intermediate vegetation cover The 1 L multiplicative term is present in SAVI and MSAVI to cause the range of the vegetation index to be from 1 to 1 This is done so that both vegetation indices reduce to NDVI when the adjustment factor L goes to zero e CH1SUR and CH2SUR are the atmospherically corrected ground reflectances in channel 1 and 2 expressed in decimals Acronym savi Unit Range Min 1 max 1 precision 20 01 15 AHAS User Guide Spectral Composites Soil adjusted vegetation index Dh ee 6 Show Mear Infrared C o Show Red DE Close Show Histogram d RI LEX M INI IM PHI UE Eu Display map Input maps for NDVI and SAVI Green leaves have a reflectance of 20 percent or less in the 0 5 to 0 7 micron range Channel 1 green to red and about 60 percent in the 0 7 to 1 3 micron rang
34. Displacement height 40 59 64 E Emissivity narrow band 24 Evaporative fraction 68 69 Evapotranspiration daily total ET24 68 69 potential PET 66 67 F Factors ground biomass 75 Fractional vegetation cover 17 Friction velocity u 57 63 H Histogram graph 80 show 13 82 table 81 Histogram equalization 14 AHAS User Guide 86 Inage identifier 77 Instantaneous total water use L 67 68 Interpolation 11 81 options 11 81 L Leaf area index LATI 17 18 21 41 44 Linear stretching 14 Map description 79 Momentum flux 58 64 68 69 N Normalized difference vegetation index NDVD 15 16 24 25 26 27 28 36 44 56 76 O Output map 79 P Photosynthetical Active Radiation PAR 71 72 Point map 50 Priestley and Taylor 19 20 66 R Radiation daily average shortwave 45 46 57 71 daily longwave net 20 49 50 83 daily shortwave incoming 20 daily terrestrial 45 50 daily total net Rng y 56 57 66 69 instantaneous longwave incoming 51 instantaneous longwave outgoing LT 54 instantaneous net Rn 54 55 59 64 68 instantaneous shortwave incoming KI 52 53 instantaneous terrestrial 47 48 53 Relative humidity 84 Resistance to heat transport zah 57 S Sahelian 18 Sensible heat flux H 58 62 63 67 68 Show map tables 82 Slicing table 78 Soil Adjusted Vegetation index SAVI 15 16 17 18 Soil heat flux G 55
35. N BUTTON FOR MAPS said ld 80 HISTOGRAM BUTTON at AAA A da 80 CORA PH HISTOGRAM db 80 EE 6l TABL HISTOGRAM td ES 81 ISE RHEIN EE 81 STATUS 7 HEP AREA EEN 82 CREATE OPUNIN BUTTON ata A A bd 82 INPUT DEPENDENCY LAUNCHER is id 82 SHOW MAP TABLES DIALOG BOX A 82 SHOW HISTOGRAM DIALOG BOX id ee 82 ADDA REMOVE BUTTON Sarai rai A DEN AE 82 SAVE AND LOAD BUTTON Sai idad 82 LISTOF MULTITEMPORAL IMAGES ii bs 83 SEOUENCING A EE 83 SELECT PROJECT EIEB IN ATLAS ee ee ee eet 83 DESCRIPTION BO Roa 83 CREATE POINT M AP eec docte etus fosse titu sa 83 ATT DUTE dE 83 AR TEMPERATUR EE 84 WATER VAPOR ERES SONES 84 RELATIVE UNID dos 84 WIND PEE Dai SE MC MULUS C 85 KINO EEN 86 AHAS User Guide Introduction to AHAS Introduction to AHAS The AHAS AVHRR Hydrological Analysis System is a GIS project based User interface over ILWIS software dedicated to the production of raster maps hydrological oriented outputs from AHVRR pre processed imagery and ground meteorological data An in built expert system guides the output elaboration minimizing possible mistakes from the user A project for AHAS is equivalent to products that can be derived from only one AVHRR image set taken by a AVHRR sensor on board of a NOAA satellite a particular date at a particular site A project is composed by several initial images and products that can be derived from them by applying dedicated methodologies Initial maps for AHAS An AHAS project requires
36. TARTING AA EE 9 ALAS EENEG 10 PROTECT WINDOW said 11 Thematic TICS A did 12 TE qusuuie sees td en I M NEP I m d 12 RICH f T 13 SPECTRAL COMPOSITBS 5 2 eorrbeee aeneo eot nto c oa enu ra bonae e eoa uso oe pend o ee eo peau eso oa roo eo eese aeu erede eve e veo Po dua a eee ret 14 COLOR COMPOST E IMAGE Susi te alode adeste eds qoa donat ii 14 Asston channels to Color DAVIS ii AAA aed AA AAA AAA AAA AAA 14 Characteristics OF the default CORREN 14 EE EE ee 14 HISTOGRAM EQUALIZATION ds 14 USCTRTCIVA SES E 14 F eanteroais OF DUC Valeo ur tu tac Oba AAA ida em ut Ada SL ORs SOI Scant po 15 NORMALIZED DIFFERENCE VEGETATION INDEX ONDNTI ee enne nennen 15 SOIL ADJUSTED VEGETATION INDEX GANTI 15 Input mapsJor NDVI dnd SAVE atis AA Re ra Yn CUR AS E EC RN AA 16 BIOPHYSICAL PROPERTIES uma dia 17 FRACTIONAL VEGETATION COVER VG ia ES a a 17 Fractional Veeetattom cover input ta AAA AAA A m AD INE saints If Procedure anasderauttoa at essesdtsvetacut a 17 PEAR AREA INDEX H ER t AAA A Eoo ep UR e taut fecti eat 17 EE 18 CROP REFLECTANCE COEFFICIENT KCR 18 Cropreflectance Coefficient UT a s ena A aid 19 CROP COBPEICTENT PRIESTEEY AND TAYLOR i ect ste bete ratae Up S ot ende PUE ee due RU I arcadwonarecones 19 Crop coefficient Priestley and Taylor input queso Ee AE pue eese fale ione Sinha RU PEU 20 TRANSPIRATION COEFFICIENT IG 2 iioond eo oues en ei o tendo os 20 Tr nsDIFation EEN 21 PLANETARY BROADBAND ALBEDO EE 21 EE EE 21 BROAD
37. The user creates opens the meteorological station point map having the same georeference as the other maps This is done from the dialog box create daily sunshine fraction Select show station show button See also point map editor e Incase the station map already exists but stations have to be added the user is requested to enter select the location of the periheliometer stations in the point map This is done from the ILWIS map windows by edit edit layer point map name After entering the station name in the point map press enter to confirm b The meteorological station point map is linked to a table containing meteorological data where the user enters attributes meteo data of different kind for each station The user is able to edit the meteodata point map and add remove meteostations See IL WIS help file ILWIS point maps e Once the station is entered or selected edit the attribute table select show table and press show button The user enters the hours of sunshine Sun hs d at the ground in hours that correspond to the available stations and press enter to confirm This information is stored in an appropriate column of the station point map attribute table When finished close the table e To initiate the calculations press OK e A raster map showing the potential hours of sunshine is automatically created by the system e The UI calculates at each station the ratio real to potential hours of sunshine and interpolates the poi
38. alculator The weight column indicates the proportion decimal of each vegetation structure in the region The weight is a multiplicative factor between O and 1 The user must verify that the summation of the weight column equals 1 4 The user must enter the vegetation structure data height spacing and breadth for each vegetation type selected in the region Each line in the calculator corresponds to one unique vegetation structure The user has to enter all recognizable vegetation types and emissivities before pressing the Apply button 5 The user must enter the emissivity of a pure bare soil and pure vegetation in each selected structure for the spectral range he she wants to work 6 Finally the user Apply the calculation The final de result weighted or averaged depending on the selection is place in the corresponding dialog box ready for further calculations The individual de results are place in the last column scroll to see it 7 The user need to enter the Pv Vegetation proportion map 8 Select a name for the output map and press Oh Aaditional features in the de calculator e Each line in the de calculator corresponds to one unique type of vegetation structure that has been identified by the user for the region under study A collection of vegetation structures several lines in the de calculator defines as it best the different types of vegetation structures available in the area This information is
39. aluation of T and To It activates after the user added the images for the Bact calculation and clicks in the corresponding row to enter T or T gt P T calculator AAA AAA SAA AAA EA l an Feb Mar Apr May Jun Ju Aug Sep Oct Nov Dec mmt T T I I 1 L 1 Month for Mas HE January sl Acquisition month of the image april sl T1 Calzuis 1 T2 Celsuish GEM Llose Procedure e The user clicks on any of the target cells T1i or T2i where the results of the calculator should place The mean monthly temperature C In total 12 data For the considered crop type c3 or c4 the user selects the month that corresponds to the maximum NDVI e The user selects the month for the calculation of T5 by changing the Acquisition month of the image drop down box e Press Apply for the calculations Results e T is unique e T varies every month so the user can recalculate monthly To values by selecting other months in the Acquisition month of the image drop down box and pressing the Apply for the calculations The calculator solve the following set of equations W A T 0 8 002 T 0 005 T opt Fexpi0 2 T 10 E 2 E exp 03 Leg KE where A is the evaporative fraction of the surface energy balance Topt C is the mean air temperature during the month of maximum leaf area index or NDVI Tmon C is the mean monthly air temperature Auxilia
40. and pixel value Add images to cursor info Press this buttons to browse for more images to add in the pixel info box Sorting keys Moves up and down the selected file in the cursor info box Coordinates Indicates the coordinates of the selected pixel in all maps The coordinates are expressed in the coordinates system units metric or degrees Amount of pixels It displays the amount of pixels having the same value in the map Map description Any descriptive name for the content of the map Output map Name of the output map The user might select any name with a maximum of 8 characters The first one cannot be a number Show button This function allows the displaying of a selected input map in the show dialog box 79 AHAS User Guide Agro ecological indicators Browse button This button allows searching for an input map anywhere in the hard drive or network to be incorporated in the project or to make part of the current process Option button for maps Allows the selection of the input maps to be displayed by the show button Histogram button This function allows the displaying of the histogram of a selected input map in the show box Graph histogram A histogram is a bi dimensional graph that shows the number of repetitions of a certain variable The X represents the variable value and the ordinate Y the number of times the variable appears in a certain collection Histogram displays by e sele
41. arimeters e Class 3 stations A less accurate but still valid approximation is for the second class stations having periheliometer data sunshine hours The final map is an interpolation from a Lday point map The user has to enter the best possible data and the UI will automatically select the best procedure to achieve the Lday value in the station In the create average daily net longwave radiation menu the user has to browse or create the following maps Raster maps e Daily terrestrial solar radiation e Daily incoming shortwave radiation e Sunshine fraction map This map is needed in case the daily incoming shortwave radiation map is not available Point maps e Point station map with the meteostations and its attribute table Procedure 1 Select all required raster and point maps To create the Lday map for the first time the user has to define e A default value for a and D from the create menu using the scroll arrows The range of values is restricted to bibliography information e The user must click the create column table button to create the columns requires for the process The attribute table will open and the user is ready to enter values AHAS User Guide 50 Climatic Characteristics e The user enters the following data per station underlined if data is compulsory the station will not be taken into account if this data is not entered Station class 1 e Lnet da watt m 2 in case it is known St
42. ation class 2 and 3 e Ed mean average daily water vapor pressure millibars Mean RH relative humidity RHmean and mean daily air temperature Ta mean C Minimum temperature Tmin C Verify he values for ae be as bel al and b e f some of the data is unknown for some stations the user should enter the undefined symbol the UI will not consider the data and eventually the station 2 Close the table once all data has been verified 3 The user might select the interpolation procedure that best fits his requirements Using moving average better results are expected 4 Give a name for the output map and click OK to start calculations Instantaneous incoming longwave radiation LJ It is the thermal energy range 3 100 um emitted by the atmosphere and its components that reaches the ground in a certain specific moment Acronym LJ Unit watt m Range Min 0 max 1000 precision 20 1 Input Files Interpolation solarmeter Station Map station r3 xd C Show Station Attribute T able station a e Show Table Output File lir Close show Histogram zd q Diaplay the histogram of the map Instantaneous incoming longwave radiation input This map has to be evaluated from ground data measured in meteostations For clear days the approach presented by Brutsaert 1975 was selected in this Ul The final raster map is an interpolation from a LY point map The user
43. ature xi Input Files morl T4 Brightness Temperature for Channel 4 Channel um T amp Brightness Temperature for Channel 5 Channel al C42 0 AVE E4 E5 2 C4 2 8 DE E4 E5 C45 0 C5 1 8 C52 0 Offset 48 1 AVE 75 DE E4 Emissivity map in channel 4 ES Emissivity map in channel 5 L 07 SG Methods to generate surface temperature Output File Surface Temperature Ulivieri el al 1992 y NM __ AA Channel 4 C Channel 5 a OK Close Show Histogram 9 Create Surface Temperature X Input Files mbr T4 Brightness Temperature for Channel 4 Channel4 Gel T5 Brightness Temperature for Channel 5 Channel gl Coefficients Used to Generate Surface Temperature Map C42 0 58 AVE E4 E5 2 C4 2 DE 0 1 w 1 118 DE E4 E5 C45 1 15 C5 1 C52 0 58 Tasas Vana ES Dffset 40 51 40 AVE 68 w 163 DE E4 Emissivity map in channel 4 E5 Emissivity map in channel 5 Do m Methods to generate surface temperature Output File Surface Temperature University of Valencia 1995 h C Channel 5 OK Close Show Histogram 9 q c QU a Coll and Caselles 1997 LA 0 39 Cy 2 34 Cas 0 78 Cs 1 34 Los 0 39 Offset 0 56 a 1 e B Ae Where oO and B are value that depend on the total water vapor column in the atmospheric profile gr cm usually between 0 to 6 Select the total water vapor in the
44. browse for a LAI map or create one from this dialog box by pressing the browse button e The user has to define a value for c that varies between 0 5 and 0 8 Default 0 59 Planetary broadband albedo It is the instantaneous hemispherical planetary reflectance of shortwave radiation between wavelengths of 0 3 and 3 um estimated from the visible channels Acronym rp Unit Range Min 1 max 1 precision 20 001 Planetary Broadband Albedo Planetary broadband albedo input r tc CHITOA te CH 2TOA According to Valiente et al 1995 21 AHAS User Guide Biophysical Properties e c default 0 035 e Ge is a weight factor for channel 1 default 0 545 e c is a weight factor for channel 2 default 0 32 These coefficients can be modified by the user Broadband surface albedo ro It is the instantaneous hemispherical surface reflectance of shortwave radiation between wavelengths of 0 3 and 3 um estimated from the visible channels Acronym ro Unit Range Min 0 max 1 precision 20 001 2 ways transmittance constant method Broadband Surface Albedo x x Input Image Planetary Albedo DutputSurace Albedo k ane Factors Used to Generate Surface Albedo C7 The albedo of a non reflective body 0 073 L S Tewi wag transmittance Factor 0 5 sf OF Close Show Histogram P Close this process Transmittance from stations opened from the constant meth
45. bute table attached were meteorological data has to be entered by the user Follows the list of variables as listed in the attribute table Parameter Meaning Observations Units station instantaneous Tai jlnstantaneousairtemperatueatstation C O Z Z HH i Instantaneous relative X humidity at V6 station Uz Instantaneous wind speed at station U stations staion Bicis iia NN IM a average Lt MN rd EE station 83 AHAS User Guide Agro ecological indicators Parameter Meaning Units Observations Dew point at minimum temperature no change Station constant cloudiness factor for Lnet da F Kin da Station constant cloudiness factor for Lnet da F Kin da Station constant cloudiness factor for Lnet da F Kin da Lnet da F N Lnet da F N radiation at station Station constant cloudiness factor for Lnet da F Kin da C C S S N p EAS a b a b A otential number of sunshine hours at hours no change station Alt Station altitude over sea level o See observation below Pres da Average air pressure at station millibar Instantaneous air pressure at the station milibar NI height blending height average station Air Temperature Air temperature is defined as a measure of the average kinetic energy or speed of the molecules in the air It is measured at meteorological station under standard conditio
46. ccept e Once the input data is fixed the user selects a name for the output PV map and press OK 25 AHAS User Guide Biophysical Properties gt Narrow band emissivity E x Input images L mpr MESI ndvi ms 8 Charnel atm corrected chic gt Channel atm corrected fene ttti i i S Gel Pixel Values on vegetation Pizel Values on ground NOVI 0 33 HDI 01 06 na Ehannell fo Channel 37 Channel Io 1 Channel 0 42 Coordinates of the pixels Col on vegetation 37 For on vegetation E Col on ground ES Fiow on ground 257 Show i SUI UU CU UTE f NDI Output Pv Channel with atm a p umm Channel with atm corrected Vegetation proportion map input Required maps e NDVI map e CH1 and CH2 are atmospherically corrected reflectances these are input maps to the AHAS project Other required values e NDVI and NDVI are the values of the user selected for pure ground and pure vegetation pixels The user interface searches for the location and value of the maximum and minimum NDVI and displays it as default e The user might accept change the location of these pixels The histogram show map and pixel info tools assist the user in the search Considerations NDVI and the NDVI are image constant values that might correspond to the minimum no water and maximum NDVI in the reference i
47. cm2 In the user interface there are 2 choices Case 1 The user interface does no assist the creation of these maps In this case the additional maps have to be entered by the user They might be created externally to the system and incorporated during the process 1 The user needs to add the external maps 2 The Ul asks for the maps required for the selected method 3 The Ul let the user browse the HD net to enter the external maps 33 AHAS User Guide Biophysical Properties 4 Pressing OK performs the calculations Case 2 The user interface does assist the creation of the additional maps required by the standard methods 1 The user selects a method for the calculation of the LST 2 The Ul asks for the maps required for the selected method 3 If the maps do not exist the UI guides to alternative methods to allow the creation of these maps and then can back to this input screen to proceed the calculations 4 Pressing OK performs the calculations Available methods For all methods e the emissivity map in for channel 4 wavelength range 5 the emissivity map in for channel 5 wavelength range AM E e 5 2 The average emissivity map for channels 4 and 5 DE Ae e The difference emissivity maps between channel 4 and 5 Default method Custom SST no emissivity Coll and Caselles 1997 No emissivity maps required This method assumes the emitter is water No emissivity map is req
48. cting a map in the file list and pressing the histogram button e rigth clicking on a file in the project window and selecting histogram graph or table from the context sensitivity menu For table histogram see here e selecting a map in a input dialog box using the option button and pressing the histogram button A Chart lol 5000 4500 4000 3500 3000 e200 w Drs 2000 1300 1000 200 60912 15 18 21 24 27 3 33 37 4 M3 45 83 52 55 38 b1 b4 BT 7 73 75 73 82 35 08 31 Value O File menu e print setup Displays the options to set up the on line printers e print print the graph The quality of the printing might improve by resizing the histogram window Chart type e bar chart Creates a bar graph with the mask sectors in the X axis and the aggregated values on the Y axis e line chart Same as before but using a continuous line e area chart Same as line chart but coloring the area under the line Select bar line or area to go from one graph type to another e Division per label Interval between labels in the X axis AHAS User Guide 80 Agro ecological indicators e Divisions per tick Interval between the ticks grid lines in the X axis Options e Show legend check to display a legend for the graph e Show X Y grid uncheck to hide the grid e Value scale Allows the zoom in out in the histogram See also here e Refresh reset the grap
49. d eventually variables for the process and later press this button The attribute table of the meteorological station map selected by the user will open and the columns required for the process will be created and eventually allocated with default values Input dependency launcher Most of the outputs requires some input information that can be both e input by the user from external sources or e created in the software itself In this latter case the software checks the existence of the required input maps among the maps available Project If some of them exists they are offered as default If they do not exist the user access the corresponding creation dialog box by pressing this icon Show map tables dialog box The dialog box display all the maps required in the process input and output The user might select the map to display and press the show button Show histogram dialog box The dialog box display all the maps required in the process input and output The user might select the map to display and press the histogram button Add Remove buttons Allows the user to add remove the selected images available in one AHAS project to from the set of multitemporal images ready from calculations Save and Load buttons Allows the user to save or load a selected set of images belonging to different AHAS projects that take part in a certain AHAS M multitemporal operation e he set file has an extension Its list time serie
50. default 1 1 The albedo is variable throughout the day having maximum values 0 6 0 7 during sunrise and sunset to minimum values during solar midday The user interface will look for default maps already in the project Total daily net radiation It is defined as the balance of incoming and outgoing short and longwave fluxes during one day Rn K q K 1 th o LA day day day day Acronym Rn day Unit watt m Range Min 1000 max 1000 precision 20 1 AHAS User Guide 56 Climatic Characteristics Total Daily Met Radiation E X Input Files B Llose Show Histogram T Close this process Total daily net radiation input All maps required for this output are created in the user interface The required input can be browsed or created from this create dialog box Inputs are e Average daily incoming shortwave radiation map e Average daily longwave net radiation map e Instantaneous broadband surface albedo map Since the broadband albedo as calculated from the imagery is instantaneous the factor c1 attempts to compensate linearly for daily aloedo averages Default value is 1 1 Sensible heat H Friction velocity u Resistance to heat Zan The transfer of heat from the surface to the atmosphere is an hybrid process of free and forced convection very difficult to evaluate Since the heat transfer depends on the wind profile and this one depends on the buoyancy effect the mathematical solution
51. distinct for each region and might be applied to several images of the same region Then once the table is completed the user has 29 AHAS User Guide Biophysical Properties the option to save the input vegetation structure data and load it in any occasion Any line a vegetation structure description can be selected for deletion by pressing the cell to thee right of the height column in the corresponding line The marker arrow activates and the line is selected To delete it press the delete button e Once a line is selected the scrolling arrows below the lt de gt input table could be used to go up and down Alternatively just select other column using the mouse If anything goes wrong in the de calculator press the Refresh button to reset the calculator Data is not lost in the operation 2 he user does not use the in built calculator e Narrow band emissivity E x Py Vegetation proportion ges End ide emissivity value Would you like to apple de calculator Option on method A e e Ge Ho vegetation structure map pus Eg Ir C Megetation structure map Specify the output E Cloze Show Histogram Database C 1 The Would you like to apply the de calculator option must be unchecked 2 The user calculates the one unique overall de value that goes as input in the corresponding cell He decides then the procedure to weight the value 3 The u
52. e Channel 2 near infra red The value is then normalized to 1 lt NDVI lt 1 to partially account for differences in illumination and surface slope L is the correction factor being 0 5 the value by default The initial construction of this index was based on measurements of cotton and range grass canopies with dark and light soil backgrounds and the adjustment factor L was found by trial and error until a factor that gave equal vegetation index results for the dark and light soils was found The user might change the default value in case is needed AHAS User Guide 16 Biophysical Properties Biophysical properties Fractional vegetation cover vc V SAVI SAVI SAVI SAVI Where SAVI is the SAVI value of the current pixel SAVI map SAVI is the value of SAVI for soils without vegetation selected from the SAVI image SAVI is the value of SAVI for dense canopies selected from the SAVI Acronym Vc Unit Range Min 0 max 1 precision 20 01 Create Fractional Vegetation Cover E uge Show Close Pa gi Soil Adjusted Vegetation Index SAW ei e el EE Species Dependent YaluefSAvId os Sal Depengent ale AVIS i Fractional Vegetation Cover Output Ir KEE Ce Show Sol Adjusted vegetation Index 5441 t Fractional Vegetation Cover Output Shom Histogram Ce Show the Histogram of Sail Adjusted Vegetation Index 5 amp 1 C Fractional Vegetation Cove
53. e 68 EVADOLA d E AA tadas 68 DATE Y TOTAL EVAPORATION TE TZ de DEE 68 Dany total evaporation TOPE A AN s 69 VOLUMETRIC SOIL WATER CONTENT EE 69 Volumetric soil water content DW ike e voii A V Ea OR laa ea b aae i dg 69 AGRO ECOLOGICAL INDICATORS e eeeesce ose eene aee eaa eaa au uan eaae aba oaa ea noia ndo cda caca ranae dapes aa raa ua ae 71 PHOTOSYNTHETICAL ACTIVE RADIATION PAR s iier tbni as 71 Photosyntheticat Active RATA RON TAPIA aaa 71 ABSORBED PHOTOSYNTHETICAL ACTIVE RADIATION APART 71 Absorbed Photosynthetical Active Radiation input eese eene eene nennen nnns 72 RE 12 ACCUMULATED AP AR ACAD ARR ui sde 13 Zo HOO ATAR DIE datar ad 73 AHAS User Guide ACCUMULATED BIOMASS BAC Vir AAA AAA OSA 74 EE eeh 74 Ground DIOINOSS TACOS niu eet eRe 75 TOC EE 76 AUXILIARY FUNCTIONS AND VARIABLES e eee eere orare aon a Eae opa een eE ena een esee eian 76 CURSOR INE EA AAA bess quo NU epit 76 IMAGE DEINE UE Rd ta 77 IMITAN er ISI Giai eu Etro tri ted mis ou td ea 77 OPO S TNT 78 SEETI TI E ERST 78 SOLAR ZENIT ANOTE MAP ee Ee 78 KEE 78 FEFA CURSOR INFO rs 79 Adad ages tOSCHESOF INTO AAA ice mtd Iq dti ut attuli 79 SORTING KEY SA A EE 79 COR RI MN EE 79 P WIN HR CAD Pdrib RN I O 79 IMAP DESCRIPTION aaa baaa eie 79 ANON SUN Hc 79 SHOW BUTION d otav intent atate etc ob Sh ns aco Ra ate ds 79 BROWSE BUTTON unica laa 80 OPTIO
54. e from the dialog box create potential daily evapotranspiration Select show station show button In case a new station has to be added initiate point editor add the station a name for it and press enter to confirm AHAS User Guide 66 Water Characteristics b The meteorological station point map is linked to a table containing meteorological data where the user enters attributes meteo data of different kind for each station The user is able to edit the meteodata point map and add remove meteostations at any moment e The user opens the attribute table by pressing column table button in the create menu or by selecting show table and press show button e The attribute table opens e he user has to complete e The Ta ga column C e The average daily air pressure Press da column millibars or the altitude Alt m per station With this point data a new temporal column to evaluate A A y at the stations is created Then an interpolation map is created from this column moving average as default The final PET hs map is calculated using the corresponding equation Instantaneous total water use L It is the total amount of water evapotranspired by crops and evaporated from the soil at any moment This amount strictly depends on the resistance to vapor flow between the evaporation front inside the soil pore and the surface roughness of vapor transport above the soil surface or between the evaporation front insid
55. e only on the selected class 2 c The user enters the e for c4 and c default 2 5 for c4 crops and A for c crops For a review on other e factors see here 2 d For each crop type 3 and or 4 and each image n images since it is a multi temporal analysis going into the calculation the user enters one value of T and one value of T Then two values of T1 and two values of T2 are required per ACAPAR image A T and T calculator is in built to assist the user The idea is to train the user on the monthly dependency of this methodology 3 Give a name to the output map unique for the calculations Ground biomass factors Gregory et al 1992 Gregory et al 1992 Russel and Ellis 1988 Gallagher and Biscoe 1978 Olioso 1987 Fisher 1983 Gregory et al 1992 cum dry matter Gregory et al 1992 shoot drymatter Prince 1991 net total production Prince 1991 net total product Prince 1991 net total production Prince 1991 net above ground prod Brassica Cowpea Lucerne Lucerne Oak Paddy lido Paddy lido Paddy cigalon Paddy cigalon Pastures Soybean Sunflower Sugarbeet Wheat Wheat Wheat Wheat Wheat Wheat Wheat gutha Wheat gutha Wheat gutha Wheat gutha C crops Corn Maize Maize Maize Sugarcane Gosse et al 1986 Varlet Grancher et al 1982 Varlet Grancher et al 1982 Gosse et al 1984 Rauner 1976 Leblon et al 1995 Wiegand et al 1989 Leblon et al 1995 Hirota et al 1978 Fische
56. e quarters the amount of water vapor required for saturation For example in the desert where the air is hot and dry the relative humidity would be much lower than in a tropical rain forest where the air is very moist Instantaneous relative humidity measured in one instant or event usually at the moment satellite imagery was taken RH Average or mean daily relative humidity average value modeled from a series of instantaneous measurements RHmean Acronym RH Unit 96 Range Min 0 max 100 precision 21 Wind Speed The measurement of wind speeds is usually done using a cup anemometer The cup anemometer has a vertical axis and three cups which capture the wind The number of revolutions per minute is registered electronically see surface roughness Acronym u Unit meter seconds Range Min 0 max 100 precision 20 01 85 AHAS User Guide Agro ecological indicators INDEX A Absorbed Photosynthetical Active Radiation APAR 71 72 Accumulated APAR AcAPAR 73 Accumulated Biomass Bact 74 Add images 10 79 AHAS M 72 73 74 82 83 Air temperature 84 Albedo planetary rp 21 surface ro 20 22 Attribute table 47 83 Button add remove 82 browse 80 create column 82 dependency launcher 23 28 82 histogram 12 80 options 80 save and load 82 show 79 C Crop coefficient 19 20 Crop reflectance coefficient Kcr 18 19 Cursor info 76 D Daytime duration 48
57. e the stomatal cavity and the surface roughness of vapor transport above the leaf surface Since this resistance is impossible to quantify the total water calculated as latent heat flux is A E Rn H G where AE is the latent heat flux Hn is net radiation G is the soil heat flux H is the sensible heat flux All units in watt m is the latent heat of vaporization MJoule kg 2 501 2 361 10 Twater C The instantaneous total water use reads as 10 4 The total water use is usually expressed in terms of latent heat AE instead of L for the calculations L mm sec Acronym L or AE Unit watt m Range Min 1400 max 1400 precision 0 1 Instantaneous Total Water Use a X Input Files Instantaneous Met Radiation M ap minst gt sof Is Instantaneous Soll Heat Flux Jon Gi SC C Sensible Heat Flux TOES Dutput File OF lose Show Histogram p Close this process 67 AHAS User Guide Agro ecological indicators Instantaneous total water use input All maps required for this output are created in the user interface The required input can be browsed or created from this create dialog box Inputs are e Instantaneous soil heat flux map e Instantaneous sensible heat flux map e Instantaneous net radiation map Evaporative fraction It is the ratio between the instantaneous energy used for evaporation latent heat flux to the total energy available for the
58. e user must select only one surface temperature map created in the system If later he wants to try a second output using other surface temperature map the user should select the new map and give a new output name Instantaneous net radiation Rn It is the result of the energy balance between the incoming and outgoing long and shortwave radiation on the Earth surface at a certain moment in time A positive flux indicates radiation reaching the surface and negative leaving it Acronym Rn Unit watt m Range Min 1400 max 1400 precision 0 1 AHAS User Guide 54 Climatic Characteristics Instantaneous Met Radiation X Input Files Instantaneous Incoming shortwave Radiation kinst gt TA a Broadband surface Albedo fo I 3ETS Instantaneous Incoming Longwave FHadiatian fim Instantaneaus Outgoing Longwave Radiation flout sor C Output File UR Close show Histogram d Close this process Instantaneous net radiation input All maps required for this output are created in the user interface The required input can be browsed or created from this create dialog box Inputs are e ry broadband surface albedo map e Kl instantaneous incoming shortwave radiation watt m e LT instantaneous outgoing longwave radiation watt m e Ll instantaneous incoming longwave radiation watt m The user interface will look for default maps already in the
59. elationship we fix the surface roughness for heat transport Z n meter 0 01 m Bastiaanssen personal communication e First estimation of the aerodynamic resistance to heat transport ran sec meters PN 0 41 u s f Create the p the moist air density map kg m It is variable with altitude or pressure air temperature and relative humidity Instantaneous air temperature and relative humidity at station was already used for the instantaneous longwave incoming radiation The map is not output of the Ul but just used in the calculations Only stations having at least relative humidity air temperature and altitude are considered suitable for o map creation Since a DTM is not available in this version we produce p map as interpolation from stations The procedure is e Estimate the instantaneous air pressure at the station millibar A new column Pressure has to be created per station The user can enter there the instantaneous atmospheric pressure if existent If it does not exist is possible to calculate it If there is one station any having both air pressure and air temperature then it is possible to use this station to calculate the air pressure for the stations that do not have barometers 5 25864 T P Io where P is the air pressure at the target station millibars Po is the air pressure at the station with barometer millibars T4 is the air temperature at the target station K Tao Is
60. ents C1 oe Regression Coeficiente C2 is Regression Coeficiente C3 oa Leaf amp rea Index Output TL EEE Ce Show Soil Adjusted Vegetation Indes Sal C Leale Area Index Dutput gt Show Histogram eee Ce Show the Histogram of Sail Adjusted Vegetation Index 5v C Leafe rea Index Dutput Display map Leaf area index input The procedure is limited to the use of the interpolation equation that is the average of many experiences developed by several authors par Ll C4 c SAVI C Default c 2 0 69 c 0 59 and Cz 0 91 The user could also select a different value from a crop dependent list or any other value In case of AVHRR imagery the LAI calculated following this methodology must be taken with caution In case of Sahelian environment a linear relationship was found between LAI and SAVI SAVI c Co If the user enters c and c only then the linear equation applies If he also enters c then the logarithmic expression does LAI Crop reflectance coefficient Kcr The Ke value is the ratio of the crop potential evapotranspiration over the reference crop evapotranspiration usually alfalfa or grass The Kc s depends on the type of crop meteorological conditions and according to several authors the driving parameters that indicates its change with time for a certain crop is the fraction of growing degree days from planting For certain crop type the ground coverage detected from RS
61. er Guide Biophysical Properties Thermal infrared broadband emissivity eO Thermal infrared surface emissivity 0 is the efficiency with which the surface emits longwave radiation at a given temperature in the 3 to 100 min spectral range Acronym Te e or es Unit Range Min 0 max 1 precision 20 0001 OF Close Show Histogram 7 ao ae Thermal infrared broadband emissivity input 1 0094 0 047 In NDVI where NDVI is the normalized difference vegetation map after atmospheric correction The procedure is fully automatic However for negative values of NDVI water bare soil and clouds the equation cannot be solved logarithm of a negative number To solve this issue the system filters some negative NDVI values 1 It uses the equation to calculate the initial emissivity map In this map negative NDVI will produce undefined values 2 The next step is the attempt to reassign a proper value of emissivity 4 1 to water bodies According to Salisbury 1992 wet bodies and wet bare soil can be assigned with the emissivity of water so the steps are e Creation of a temporal emissivity map tempemi Iff NDVI lt 0 1 1 0094 0 047 In NDVI e The temporal emissivity map is filtered for emissivity values less than 0 91 e Final emissivity map iff tempemi 0 91 0 91 tempemi Narrow band emissivity This procedure is valid for a certain wavelength range where the emissivity is calculated Most
62. ested range 0 3 to 1 2 e c1 default 0 37 seems adequate for cylinder type of vegetation b h 1 for higher b h ratios larger c1 might be Tested range 5 to 1 Surface roughness and displacement height values 0 0024 Completely open terrain with a smooth surface e g concrete TT runways in airports mowed grase e i Oraa scattered buildings Only softly rounded hills hedgerows with a distance of approx 1250 meters hedgerows with a distance of approx 500 meters Ball tall sheltering hedgerows with a distance of approx 250 meters NN Trees and very E uneven tra hedgerows forests and very rough and uneven terrain 0 8 Larger cities with tall buildings o 1 6 Very large cities with tall buildings and skyscrapers Source Wind Power Denmark AHAS User Guide 42 Biophysical Properties y YO Les E S El ALA 1 13 or OB 09 Bm L po ralio of wind at height z to wind at 0 metres Source Weiringa 1977 43 and 1980 967 WMO permission ERES 0r 31 Ges Com 52 Ges Grass 58 Gam Cost 55 uenee 27 8 Deene 53 e Maze i4 ix Bush 30 350 Orange orhard ner 11551 se 5 Berey 100 Sugarcane Hawaiian Sugar 88 65 Beer TU H planers 1559 78 e Batey Ces 9 Bee Caos 105 Bee
63. g a uniform height in the area in m despite the error in the calculations See also vegetation structure Three coefficients are also required e Unobstructed bare soil drag Cs Default 0 003 41 AHAS User Guide Biophysical Properties e Overstore drag coefficient Cr Default 0 35 e Constant Cw Default 2 About these coefficients the Author says e The value of Cs es equal to u uh 2 The original value of Raupach 1992 is Cs 0 003 This value should be suitable for row crop and tiger bush sites where the ground is bare soil It is probably too small for Savannah sites where the ground is grassed beneath the shrubs Using the previous equation different values of Cs can be calculated from data available in the literature for long grass and heather Cs 0 018 Because of the Savannah grass is rather sparse an intermediate Cs 0 010 is adopted for this type of vegetation In Raupach 1992 an overstorey drag coefficient Cr 0 3 is chosen for bush like obstacles this value is between 0 25 vertical axis cylinders and 0 4 cubes see vegetation structure Values between 0 25 to 0 8 were tested The optimized value for a very wide range of vegetation varying from sparse to dense was 0 35 e The Cw constant to be found from empirical data A value of Cw equal to 2 was adopted by the author since fits the value of the vegetation influence function of unstability Other coefficients involved in the method are e cd default 0 6 t
64. he image since the method originally applies only in this case If the user confirms the minimum value of r is offered to the user as c default If he rejects then c is re mapped to min rp 2 The user is prompt to accept or modify this value e The Ul gives some standard tools to select a better value r map display pixel info and Tp histogram e Finally the user must confirm the default or enter a new value for CG 3 The determination of the c factor There are two options Case a there is no ground information on incoming SW radiation on the ground e The user enters a uniform value of Ge for the entire area default 0 5 Case b There are ground pyranometers available in stations in the area a There is ground data from a pyranometer or solarimeter in one or more locations b A new map called instantaneous terrestrial shortwave broadband solar radiation has to be created c The user creates opens the meteorological station point map having the same georeference as the other maps Select open solarimeter station map show button See also point map editor e The user is requested to enter select the location of the solarimeter stations in the point map This is done from the ILWIS map windows by edit edit layer point map name After entering the station name in the point map press enter to confirm d The meteorological station point map is linked to a table containing meteorological data where the user enters a
65. his case the de term is a map calculated by the user using GIS techniques Each combination soil vegetation might have one value of de The procedure is exactly the same as in the previous case 3 except that the de is used for further calculations and not the averaged de 4 Calculation of the narrow band emissivity In all cases the following equation applies U R BR tesde E Procedure 1 The user has to identify his emissivity application case 2 The user must enter data that is common for all cases Pv Vegetation proportion map This map must is not the fractional vegetation map as was built in the biophysical properties menu in the Ul In order to build the map the user might press the dependency launcher button The operation triggers a procedure were the system searches for the highest and the lowest NDVI pixel in the image For these pixels the atmospherically corrected reflectances in channel 1 and 2 are place in the dialog box The user can display the histograms and maps in order to verify correct the input data If the user wishes to change the default selected values he must enter the new column and row for the pure vegetated and or bare soil pixel and press enter to accept e Once the input data is fixed the user selects a name for the output PV map and press OK By default the Create narrow band emissivity dialog box opens for cases 1 and 2 In case the user is in cases 3 or 4 vegetation
66. hness involved in the H equation depends on the sensible heat flux itself to account for buoyancy effects The solution is straightforward only in case of neutral condition where H theoretically tends to zero aerodynamic resistance tends to infinite Most likely this is not the case in daytime imagery so in the following the theory adaptation implemented for the case of the AVHRR imagery is described in detail The steps described here are the heart of the evapotranspiration estimation process The results will mainly depend upon initial conditions selected by the user at the first stage of the process This means that the user might review and or recalculate several times The user interface is prepared to offer the best help possible but still the fact that this process is user controlled remains To obtain good results requires user expertise to fix initial conditions to analyze outputs and to review conditions in order to improve the outputs Initial data Haster maps Some maps have to be prepared or available to initiate the interaction process The user can AHAS User Guide 58 Climatic Characteristics browse in the project to input them or build them during the process e Surface roughness for momentum transfer Displacement height Surface temperature Instantaneous net radiation Soil heat flux Point meteorological data e The user has to enter data in the meteorological station point map in fact in its attribu
67. hs to the selected options Use after setting Value scale Characteristics e Select the maximizing icon to obtain a full picture e he assignation of color is automatic Value scale Allows to zoom in out in the histogram min max X enter the minimum and maximum value to zoom in the X axis min max Y enter the minimum and maximum value to zoom in the Y axis Press OK to accept To see the zoom effect press the Refresh option from the Option menu Table histogram This function displays a statistical table with numeric information on the histogram of a certain map in AHAS The histogram is a typical ILWIS histogram table A histogram table can be accessed First by selecting a map in the project window e From the main window select View Histogram Table e From the project window by right clicking on the image and selecting Histogram Table from the context sensitive menu Tig Eun oran pons Ben value mnpix Inpixpct npixcum npcumpct Area x 2001 304 479 1558 1 73 43486 48 32 0 2 201 304 580 1134 1 26 44620 49 58 0 1 202 304 682 1123 1 25 45743 50 83 0 1 203 304 784 1587 1 76 47330 52 59 0 2 204 304 886 1395 1 55 48725 54 14 0 1 205 304 998 1144 1 27 49869 55 41 D 17 2 6 305 092 1445 1 61 51314 57 02 0 1 207 305 194 1602 1 78 52916 58 80 0 2 208 305 296 1065 1 18 53981 59 98 i TAO Lb 30 19204 1 AL LEO Gil 4 1 d d Double click to change column properties of nok Humber of pi
68. ig Daily incoming Shortwave Solar Hadiatian Kinda ze E C Daily Net Longwave Radiation JInetnn a RE C ci 11 0 v Apply Mask Name of the mask mpr gt C OF Close Show Histogram p Crop coefficient Priestley and Taylor input The maps required for these calculations are e Broadband surface albedo e Daily incoming shortwave solar radiation e Daily net longwave radiation e Raster map called mask indicating the irrigated and no irrigated fields The map must have the same georeferencing of the other maps in the project and a domain CLASS with only two class types irrigated no irrigated Care with the spelling otherwise the calculation will fail Other inputs e A conversion factor for surface albedo to convert the instantaneous surface broadband albedo in a daily average broadband albedo default 1 0 e n case the user decides to apply the calculation to the irrigated areas then the user must enter the mask and check the Apply mask box If it is not checked the calculation apply for the entire image Transpiration coefficient tc It is the fraction that results from dividing unstressed transpiration by potential evapotranspiration Acronym tc Unit Range Min 0 max 1 precision 20 01 AHAS User Guide 20 Biophysical Properties Transpiration coefficient input e A Leaf Area Index LAI map is required The UI will detect one of the available in the project The user might
69. in case of a perfect clear day Acronym N Unit hours Range Min 0 max 25 4 precision 20 01 Create Daytime Duration zi Br Llose Show Histogram 7 nn Diaplay the histogram of the map Daytime duration input Since the user interface has a simple and accurate in built solar radiation model the only data required is the date for the calculation The other data required position on Earth is read by the system from the lat long coordinates assigned to the image selected by the user the solar zenith angle map by default Sunshine fraction cc It is the ratio between the real number of clear sunshine hours per day and the total daytime duration for an specific date AHAS User Guide 48 Climatic Characteristics Acronym cc Unit Range Min 0 max 1 precision 20 01 Create Daily Percentage Cloud Cover X Input Files Interpalatian pm ee A AA A A ARN AAA AAA E A E Gn Gi e e Ge Ma A E Gm MER Geri E A ES EE OE ec E aca ami amp Hun ta Create Solanmeter Station M ap See Potential hours of sunshine Sunshine fraction input Daily sunshine fraction in the user interface can be entered by e importing to the project an external daily sunshine fraction map having the same georeference that the other maps e Calculating sunshine fraction point data in the available meteostations using available interpolation methods In the second case the user proceeds as follows a
70. in for of vegetation indexes gives the indication of stage development and so days after planting This is the concept behind the crop reflectance coefficient Ak c SAVI c Defaults c 1 461 Ges 0 017 wheat Acronym Kcr AHAS User Guide 18 Unit Biophysical Properties Range Min 0 max 2 54 precision 20 01 Create Crop Coefficient p Histogram Show Close Lo Sall Adjusted Vegetation Index SV savi pe 4 Regression Coeficiente ET AET Regression Coefficients Cz om 7 Crop Coefficient Output A Showy hd ar A a a Ce Show Soil Adjusted vegetation Index 5541 C Crop Coefficient Output show Hita eee Ce Show the Histogram of Sail Adjusted Vegetation Index S441 ge Coefficient Output Crop reflectance coefficient input Crop coefficients default c 1 461 c 0 017 valid for the case of wheat The user could also select a different value accordingly In case of AVHRR imagery the Kcr calculated following this methodology must be taken with caution in case of impure pixels Crop coefficient Priestley and Taylor Definition the ratio of crop potential evapotranspiration to the evapotranspiration of a reference crop usually grass or alfalfa Acronym Kc Unit Range Min 0 max 2 54 precision 0 01 19 AHAS User Guide Biophysical Properties Crop Coefficient Cd x Input Files Broadband Surface amp lbedo luesen Gi 7
71. in the mask must be undefined so calculations do not perform on these pixels The domain for this raster map must be CLASS It must have only two items named c3 and c4 The map must have the same georeference as the other maps in the project The user might decide to apply the calculation to all pixels in the map by untagging the apply AHAS User Guide 74 Agro ecological indicators mask option In this case it is not possible to differentiate a cropped pixel from a non cropped pixel and between the two pixels with distinct crop types By default the UI sets that all pixels in the image are crop CLASS c3 The user might change to CLASS c4 but no other options are available e here is a choice of not entering the mask by unchecking the crop map option This option should be rarely used since the Ul assumes that the entire map has be treated as a field with one unique crop type In this case the user has to define the crop type to perform the calculation In this case c3 is default 2 Other maps and values 2 a The AcAPARi images see AcAPAR input 2 b The user has to enter the evaporative fraction map and period of validation seconds that correspond to each AcAPARi image 2 C The user selects whether calculations are performed for c5 c4 or both e n case a crop mask is entered it will be use to apply the correct coefficient to each crop type e f calculations are performed on c3 or c4 exclusive the mask is used to calculat
72. ions of these two pixels and their values will be stored in memory and are going to be used to calibrate the algorithm A linear near surface temperature difference AT surface air temperature relation is derived from these wet and dry pixels Objective The user has to be able to select the driest and the wettest pixel in the image The driest pixel is considered to be that one having the highest temperature as default The user is free to take it or change it The wettest pixel is evidently areas having water on surface The surface temperature of these water pixels is considered to be the same as the air temperature In case of cloud free images these pixels might been the coldest in the image The UI might offer this coldest value as default Stored data e The position of the driest and wettest pixels as given by the user X y ay X Y we e The surface temperature for these pixels as extracted from the T map Basic tools in the UI to allow a good decision from the user e Display the histogram for the surface temperature map T e Display the T map e Activate the pixel info window and the surface temperature map Iteration process The process initiates by extracting initial values from pre existing maps a Using the location of the dry pixel x y a The system retrieves and stores e The surface temperature of the dry T ary and wet pixel T wet K e The net radiation in the dry pixel Rng watt m e
73. is case the user must enter another column eg as an attribute for the vegetation map 31 AHAS User Guide Biophysical Properties de calculator spreadsheet If the user is in cases 1 or 2 he or she has to decide a unique value of de for the calculations A calculation box is designed to assist in this purpose There are 2 version of the de calculator online and spreadsheet The on line calculator is designed for map production The spreadsheet see helpfile is designed for both map production and training Exclusive input and outputs for spreadsheet are in blue The inputs boxes are H height m S spacing m L breadth m Ev Eg Satellite view angle Y The output boxes are related to vegetation structure and the de term Percentage of top vegetation L L S rounded to 1 decimal Percentage of side vegetation H L TAN W S L Y is the satellite zenith angle Percentage of ground vegetation 1 Pt Ps de 1 eg ev F Pg 1 ev eg G 1 ev ev F Ps demax 1 eg ev F 1 Pt weighted or not e ev Pt ev Ps eg Pg e CH B exact de approx 4 lt de gt Pt Ps 1 Pt Ps Capprox V Pt Ps e9 Pg dE approx Capprox this difference to check the accuracy of the approximate model Online lt de gt calculator 1 If the user is in case 1 then select Average de emissivity value in the Option on lt de gt calculator The weight column must be kept empty 2 If the user is in ca
74. issivity map in channel 4 correspondent buttons before the final ES Emicsiviymapinchanrel5 Tel calculations 0000 8M E AA S Show ls e Channel 4 C Channel 5 d us OK Close Show Histogram R 0000000 00 Kerr et al 1992 C eo 0 Create Surface Temperature xj C 2 0 5 P 3 1 Input Files f mnrl S S i C 0 a Fee T4 Brightness Temperature for Channel 4 ham 457 Ces E 0 5 P 2 1 T5 Brightness Temperature for Channel 5 Jeng gt D D V D SE SS S SE Sas NN HE Cs n 0 uices Used to mU Temperature Map j Offset 3 1 5 5 P C42 0 C4 0 5Pw 3 1 Where E SW NDVI E NDVibare soil NDVlij vegetation 52 0 N DV pare soil ffsetz3 1 5 5 Pv Where Pv is a vegetation percentage map base on the NDVI P is a vegetation cover percentage map based E A ay on the N DVI Methods to generate surface temperature Output File Surface Temperature err et al y NDVlbare soy is the NDVI of the bare soil selected ERG B by the user Default the minimum NDVI from all E Won Wool D positive NDVI values Ok Close Show Histogram Y NDV liu vegetation IS the NDVI of fully vegetated pu uu uu re T T pixels selected by the user Default the maximum NDVI value AHAS User Guide 36 Ottle and Vidal Madjar 1992 Co 0 C user entered Les 0 Cs user entered Loss 0 Offset user entered Sat scan angle 0 9 16 23 32 38 44 48 53 0 53 0 53 0 53
75. lds of this dialog box In this case AHAS User Guide 64 Climatic Characteristics itis not necessary to enter the value in K of the user selected wettest and driest pixels Parameters Some calculation parameters must be entered in the dialog box e he blending height m At blending height roughness effects are negligible and wind speed might be considered areally constant Default 100 m e The height reference at which momentum fluxes apply is called Z m This value has to be decided by the user Default 5 m Important e Before offering this value as default the user interface checks that none of the pixels in the zero height displacement map d has a value bigger than 5 m If this happens the default value is changed to max d 1 meaning the maximum value in the d map 1 e he user is able to change the default to another value After the change the user interface checks this condition and warns the user about the existence of d values higher or equal to the ze selected by the user In this case the interface allows the user to review the value or accept the errors that will happen as undefined values in the final maps e The air specific heat at constant pressure c Joules kg K Default 1004 16 e The height at which the final wind speed output map is calculated u m 65 AHAS User Guide Agro ecological indicators Water characteristics Potential evapotranspiration PET24 Definition the depth of
76. likely the user will estimate the emissivity maps in channel 4 and 5 It attempts to estimate narrow band emissivity from vegetation index maps and pure emissivity values To redo the procedure for other wavelength range the only values that change are the emissivities for the bare and pure vegetation pixels The rest of the procedure remains the same There are four application cases going from the simplest 1 to the most complete 4 e Case 1 No vegetation map nor soil map is available no idea of the spatial distribution of the vegetation exists no information on vegetation structures e Case 2 No digital vegetation soil map is available but analog or tabular Information do exists on vegetation structures e Case 3 There is a digital vegetation map and vegetation structure information If the soil map is not available it is built from the vegetation map The user recognizes that vegetation heterogeneity is predominant and the vegetation map only identifies main vegetation structures e Case 4 Digital vegetation maps and structure available Digital soil map available or not If the soil map is not available it is built from the vegetation map The user is confident that the vegetation map reproduces the heterogeneity found in the field AHAS User Guide 24 Biophysical Properties Concepts and procedures 1 Determination of the NDVI based vegetation proportion 1 NDVI NDVI A A 1 NDVI NDVI K 1 NDVI NDVI
77. ly incoming shortwave radiation K day The horizontal integrated daily value of the solar radiation over all wavelengths reaching the ground Acronym KJ gay Unit watt m Range Min 0 max 1400 precision 20 1 Note The total solar energy reaching the ground in 24 hs cumulative it would be in megajoules m day TL To obtain watt m multiply by 11 5741 45 AHAS User Guide Climatic Characteristics Daily Incoming Shortwave Broadband Solar 0 00 x Input Files Interpolation solarmeter Station Map station i rd i Show Station Attribute T able station Ez C Show Table Daly Extraterrestrial Shortwave Solar Fadiation Jkidaypl gt C Show Exo Shortwave Solar Radiation Daily Percentage of cloud Cover cleo f C Show Percentage of Claud Cover EE SS UK Close Show Histagram En T Average daily incoming shortwave radiation input Useful unit equivalences 1 Joule 1 watt sec Instantaneous radiation watt m 2 Solar energy radiation time watt sec m 2 Joule m 2 Average solar radiation in 24 hs radiation daytime 24 hs Joule m 2 24 hs watt m 2 The final Kl map has to be evaluated from ground data measured in meteostations e First class meteostation might have this value as a standard reading using solarimeters e Second class meteostation might not have the solarimeters but some approximation to the real value is possible if these
78. mage 2 Determination of emissivities for pure pixels The emissivity values for the pure ground e and pure vegetation e pixels have to be entered by the user Considerations e The emissivity of the pure ground can be as high as the vegetation in case that the ground is covered with vegetation Typical case is the fallow Savannah covered with perennial grasses e The values are applicable to any wavelength range selected by the user e For each unit considered by the user see cases one unique value for e and one for e has to be defined However only in case 4 the user needs to enter all these values for the calculations e Alternatively some background information and tables will be available where the user can have some reference values 3 Determination of emissivity correction term lt de gt AHAS User Guide 26 Biophysical Properties Concept de is a correction for the emissivity non linearities with NDVI It is a function of vegetation structure and satellite view angle de is always a raster map In cases 1 2 and 3 this map assumes a constant value This is mainly due to lack of information from the user In case 4 de is a variable raster map de in the different cases The user is in case f In this case the de is only one unique value entered by the user The user should investigate a mean value of lt de gt based on a number of observations vegetation and emissivities for a reasonable n
79. n of a near real time solar zenith angle map for the georeferenced project image One of the eleven inputs linkID 1 of an AHAS project is a solar zenith angle map Usually the NOAA AVHRR pre processing software creates this map and in this case the user should not use this option e Cloud masking techniques not fully implemented yet Project window The project window is dedicated to the management of all files belonging to one unique AHAS project Basically it is design to e Keep a list of all files in the project e Operate as a file manager e From six thematic menus the user launches output operations for all products in the AHAS 11 AHAS User Guide Introduction to AHAS LC SHbspxImagex5E T 3Xtest3 hpr Spectal Compostes Eiephysical Froperties Climate XD Cd iatactenstice ww aterert ties rst cologica Flannng logation dndicator Channel Hbsp lmage SET 3 Reflectance maps in channel 1 Reflectance maps in channel Channel L sRHbsp Image SET3 Brightness temperature for cha Channels LC Absp image Se TS Brightness temperature for cha Channel L Hbsp lmage sSET3 Brightness temperature for cha Channels L Hbsp lmage SET3 Solar zenth angle map Solzen LA Abspslmage S5ET3 satellite zenith angle map List of files file types and file location in he current AHAS project The list all huttom displays all files in the project Solar azimuth angle map Satellite azimuth angle
80. n one or more locations b The user creates opens the meteorological station point map having the same georeference as the other maps This is done from the dialog box create instantaneous incoming shortwave solar radiation Select show station show button In case a new station has to be added initiate point editor add the station a name for it and press enter to confirm See also point map editor c The meteorological station point map is linked to a table containing meteorological data where the user enters attributes meteo data of different kind for each station The user is able to edit the meteodata point map and add remove meteostations at any moment See IL WIS help file ILWIS point maps e The user opens the attribute table by pressing column table button in the create menu or by selecting show table and press show button e The attribute table opens For stations having solarimeters the user is requested to enter the value of the incoming solar radiation at the ground column Kin i in watt m at the moment the image was taken in the station This information is stored in a column of the station point map attribute table The information might have been entered earlier 53 AHAS User Guide Climatic Characteristics e For stations without solarimeter data enter the undefined character in the corresponding column Kin i e Based on this point map attribute table via scripts another column is created without user interac
81. ns Instantaneous air temperature measured in one instant or event usually at the moment satellite imagery was taken Ta Average or mean daily air temperature average value measure from thermographs or modeled from min max daily values Ta mean Acronym Ta Unit C Celsius Range Min 20 max 70 precision 0 01 Water Vapor Pressure Actual Vapor Pressure ea is the measure of the air s actual water vapor content Saturation Vapor Pressure es is a measure of the air s TOTAL capacity for water vapor Instantaneous water vapor pressure measured in one instant or event usually at the moment satellite imagery was taken ed or es Average or mean daily water vapor pressure average value modeled from a series of instantaneous measurements ed mean Acronym ed or es Unit milibar Range Min 0 max 100 precision 20 01 Relative Humidity Relative humidity is the ratio of the amount of water vapor actually in the air compared to the amount of water vapor the air can actually hold at that particular temperature and pressure Ta0 is the instantaneous air temperature at the station having barometers There is no difference between Ta0 and Ta i Then to avoid repetitions Ta0 column should be deleted The UI should use Ta i for the calculations AHAS User Guide 84 Agro ecological indicators Since relative humidity is given in terms of percent 7596 relative humidity means that the air contains thre
82. nt map using an interpolation method selected by the user c The map sunshine fraction map is produced with the available data Average daily net longwave radiation Lday This map evaluates the significant change of radiant energy between the atmosphere and the earth s surface in the longwave range 3 100 um 49 AHAS User Guide Climatic Characteristics Acronym Lay Unit watt m Range Min 1000 max 1000 precision 0 1 Create Daily Net Longwave broadband Solar Radiation X Input Files Interpalatian solarimneter station M ap station gt Ed Show Station Attribube Table station c d Ce Show Table Daily Estraterestial Shortwave Solar Hadiatian fkidaypi Ed C Show Exo Shortwave Solar Radiation Daily incoming shortwave solar radiator ord C Show Daily Incoming Shortwave Radiation Daily Percentage of cloud Cover BE toe ee C Show Percentage of Cloud Cover Dutot Eer Correlation coefficient ee RS Se 1034 Be 014 5 OK Close Histogram sd T pe Close this process kdau Average daily net longwave radiation input This map has to be evaluated from ground data measured in meteostations e Class 1 meteostations might have this value as a standard reading using in out thermal radiometers e Class 2 stations might not have the radiometers but some approximation to the real value is possible if these stations have solarimeters First class stations might also have sol
83. o create new inputs for AHAS Once the Map Calc menu is opened the user is able to enter an ILWIS map calc statement as it is when working with ILWIS The calculated map can be added into the current AHAS project by following the add image procedure explained above The current directory for the ILWIS Map Calculation goes to the working directory of the project file automatically when ILWIS Map Calc opens This function adds top flexibility to the AHAS currently programmed methods e Image identify This function allows an image classification into slices of user selected intervals e Interpolation options Ground data from meteo stations point data usually needs to be interpolated to the entire image In this version AHAS system allows to simple interpolation techniques nearest neighborhood and moving average Some outputs have shortcuts buttons in input data dialog box to let the user fix the interpolation method If the shortcut does not appear in the input dialog box it means that one interpolation technique is preferable over the other and the user interface set it as default In any case the user might change the interpolation technique by accessing the interpolation options through this menu before proceeding to the calculations e Image preprocessing These options are alternatives the user might choose to pre process the raw images before they become part of an AHAS project e Solar zenith angle map This option allows the creatio
84. od Es FEoaa wau transmittance map Solanmeter Station M ap eg Gi z Attribute T able station Gi interpolate py 1 f Show Planetary Albedo Terrestrial radiation Open Station OpenTable Bk Close Shaw Histogram Y ub this process Broadband surface albedo input p oc r RH Cg According to Chen and Ohring 1984 and others C7 is the offset in the relationship between broadband planetary albedo and broadband surface albedo The albedo of a non reflective body deep sea water appearing in the image or not Cg It is the two way transmittance of the broadband shortwave radiation There are two built in procedures in the user interface a The user enters the 2 way atmospheric transmittance 0 5 by default b The system calculates it from ground station data from pyranometers AHAS User Guide 22 Biophysical Properties a It is the default method b This method can be accessed by using the input dependency launcher button next to the Gel input in the default create screen Input requirements 1 The planetary albedo map rp must be calculated already 2 The user must decide a value for cz The user interface provides the tools to allow the user a right selection for this value e The histogram of rj might be calculated and displayed e IMPORTANT The minimum value for ere map is automatically determined by the system The user must confirm the existence of deep sea water in t
85. one date This function opens a dialog box where the user enters relevant information to identify the characteristics of the original NOAA image and the AHAS project itself Set working directory The user can define a directory where to store all outputs files generated in the current AHAS project e Add images allows the user to add ILWIS images stored externally into the current AHAS project Important to incorporate a raster image into an AHAS project this must be an ILWIS file having the same georeference as all other images in the project First select the type of image to be incorporated by choosing the right one from the drop down menu Then browse in the HD or network to get the image by pressing select image Finally press add to add it into the system e Add image date many outputs required the image acquisition date The user might inter it here Format mm dd yy e Remove image Allows the simple or multiple image deletion from the project Select the image s to delete from the project window Select Project remove images from the main window alternatively select the icon in the project window Note This function removes the file from the project but it does not delete the file lt remains in the working directory and it can be added in any moment using the function add image To delete the image permanently use the your file manager software View e Map window Displays the image selected in the
86. press the create button to initiate the corresponding dialog box and the input procedure Adding images It allows the user to add ILWIS images stored externally into the current AHAS project Important to incorporate a raster image into an AHAS project this must be an ILWIS file having the same georeference as all other images in the project AHAS User Guide 12 Introduction to AHAS First select the type of image to be incorporated by choosing the right one from the drop down menu Then browse in the HD or network to get the image by pressing select image Finally press add to add it into the system Context sensitivity menu Right click an image displayed in the project window list to access the context sensitivity menu which summarizes the most significant functions for images in AHAS e Show map displays the map e Show histogram graph displays the graph histogram table displays the table histogram e Show pixel info access the cursor info function e Image properties Displays the characteristics of the file The user can add comments on the file type Tips and Tricks e When performing the calculations be sure that all ILWIS pixel Info box map windows and tables must be closed e Preferably install IL WIS in the default directory cAilwis22 e ILWIS works independently from AHAS so you might use it at the same time but never when AHAS is performing a calculation In this case be sure that all ILWIS pixel Info
87. project Soil heat flux G During daytime some portion of the energy available at land surface passes through the land surface and is used to heat up the soil It composes the soil heat flux The flux goes away from the surface and is negative by convention although in the maps positive values appear for simplicity During nighttime the soil is warmer than the surface and the flux is inverted In the latter case the flux is positive going to the surface Acronym G Unit watt m Range Min 1400 max 1400 precision 0 1 55 AHAS User Guide Climatic Characteristics Instantaneous Soil Heat Flux x Input Files Surface Temperature Map price a E O Broadband Surface Albedo Jo gt ser IC Instantaneous Met Radiation M ap nns 0 F C Normalized vegetation Indes M ap REIN gt SF C Dutput Ln pe Conversion Factor of Surface Albedo PO c1 Ll OF Close Show Histogram P EE Soil heat flux input All maps required for this output are created in the user interface The required input can be browsed or created from this create dialog box Inputs are e LJ broadband surface albedo map e To surface temperature map K e Bn instantaneous net radiation map watt m e NDVI normalized vegetation index map The conversion factor for surface albedo is the ratio between the average daily albedo to the instantaneous albedo as it is derived from the visible band image
88. r 1983 Daughtry et al 1992 Joel et al 1997 Kennet 1981 Gallagher and Biscoe 1978 Asrar et al 1984 Green 1987 Gosse et al 1986 Garcia et al 1988 Fischer 1983 Gregory et al 1992 Gregory et al 1992 Belford unpublished Siddique et al 1989 Daughtry et al 1992 Maas 1988 Williams et al 1968 Varlet Granchet et al 1982 Varlet Grancher et al 1982 75 Prince 1991 net above ground prod Prince 1991 net total product Prince 1991 net total product Prince 1991 net above ground prod Prince 1991 net above ground prod Leblon et al 1995 above ground Leblon et al 1995 biomass Leblon et al 1995 Leblon et al 1995 Prince 1991 net above ground prod Daughtry et al 1992 dry phytomass Joel et al biomass Steven et al 1983 Prince 1991 net total product Prince 1991 Prince 1991 net total production 1997 above ground dry Prince 1991 net above ground prod Prince 1991 net above ground prod Prince 1991 net above ground prod Gregory et al 1992 cum dry matter Gregory et al 1992 shoot drymatter Gregory et al 1992 shoot drymatter Gregory et al 1992 shoot drymatter Daughtry et al 1992 dry phytomass Maas 1988 above ground dry mass Maas 1988 above ground dry mass Prince 1991 net total product Prince 1991 net total product AHAS User Guide Agro ecological indicators T Calculator This is a calculator box available for the user to perform the ev
89. r projected line from the same terrestrial location to the current sun position Acronym SZA Unit 9 Range Min 0 max 90 precision 20 01 Creation of Solor Zenith Angle Map 7 fei x Input Parameters Georeference File Loft IDITEEEEES Acquisition Date mmddyy bam Local Time hh mm hoss Standard Meridian West feasti5 gj BST Output File DK Meridian Close m e E Type the input parameters for generating solar zenith angle map Solar zenith angle map input All maps required for this output are created in the user interface The required inputs are AHAS User Guide 78 Agro ecological indicators e The georeference file grf This file is created after an ILWIS map is georeferenced It is very advisable that all images in one RBPS projects have the same georeference file The latitude and longitude for each pixel is derived from here and used in the calculations AHAS can handle lat long and rectangular coordinates e Acquisition date for the image The format is expressed in the dialog box e Local time for the image as read from a clock located in the center of the image This time depends on the country and the DST daylight saving time adopted for some countries See note below e Standard meridian It is the meridian that corresponds to the time zone adopted for the country The Earth is divided in 24 s
90. re Output File Surface Temperature Price 1984 Show so GG Channel 4 C Channel 5 OK Close Show Histogram RQ Becker and Li 1990 Car 0 C 3 63 2 06808 1 e 18 924 Ae amp Ce 0 Cs 2 63 1 91192 1 19 406 Ae e ee 0 Offset 1 274 Required maps Emissivity in channel 4 and 5 Required procedure Calculate AVE and DE maps by pressing the correspondent buttons before the final calculations Prata and Platt 1991 Semi empirical uses a radiative model Cao 0 Lu 3 46 Cas 0 Cs 2 46 es Coo 0 Offset 40 1 4 2 3 1 5 1 C4 C5 Required maps Emissivity in channel 4 and 5 Required procedure The constants a 3 46 for C and b 2 46 for C5 are defaults valid for Australian radiosondes authors Based on a wide range of atmospheric cases a wider range of values are 3 46 lt a lt 4 513 and 2 46 lt b lt 3 513 The user might be able to change these defaults but be aware that in any case always az b 1 35 Biophysical Properties Create Surface Temperature x Input Files morl T4 Brightness Temperature for Channel 4 Channel T5 Brightness Temperature for Channel 5 Channels Gel Coefficients Used to Generate Surface Temperature Map C42 0 AVE E4 E5 2 E423 63 2 05808 1 AVE J AVE 18 324 DE ett DE E4 E5 C45 0 C5 2 53 1 81132 1 AVE JAVE 13 406 DE
91. rfCutput Fractional vegetation cover input SAVI is the SAVI value of the current pixel SAVI map SAVI is the value of SAVI for soils without vegetation selected from the SAVI image SAVI is the value of SAVI for dense canopies selected from the SAVI Procedure and default values e The user interface automatically calculates the maximum default for SAVI and minimum default for SAVI pixel values from the created SAVI map The maximum and minimum value must be entered before proceeding to calculate v e f the minimum SAVI is negative means presence of water SAVI maps are not filtered negatives remain However for the calculation of the fractional vegetation cover it should not be an option for the user to change the minimum SAVI value In case the minimum SAVI is negative the default for min SAVI is changed to zero e The UI allows displaying the SAVI map to modify or verify these defaults The user might select a maximum SAVI value from the screen using pixel info and the histogram of the SAVI map At the same time a histogram of the SAVI could be displayed Leaf area index LAI The LAI is the cumulative area of leaves per unit of land at nadir orientation 17 AHAS User Guide Biophysical Properties Acronym LAI Unit Range Min 0 max 10 precision 20 01 Se Leafe Area Index 2 x DR Histogram Show Close 7 Soil Adjusted Vegetation Index SAW e 1 amp el Regression Coettici
92. ry functions and variables Cursor info e Pixel info allows you to interactively inspect values in one or more raster maps Once this option is invoked a collection box appears AHAS User Guide 76 Agro ecological indicators First open one any AHAS map preferably one if user interest Open the pixel info box The user could pick one by one images from the project window drag and drop them in the pixel info box By clicking on any specific pixel in the map the pixel value and amount of pixels with the same value is transferred and displayed for all maps listed in the pixel info box Cursor Info E zig xj A 27 0 T 24 0 Image Mame Pinel value Histogram FECE421he B2 42 45 0 68 0 58 Image identifier This function allows a crude image classification according to interval values selected by the user Identify Bl x File View Option Help Map Name mpr L Hbsp mage sSetl And Cols and Rowe 300 300 Min 0 06 Mas 1 Iaeareference Coordinate system latlon csy File description Normalize difference vegetation index Open a map ta dispaly EZ Image identifier menu File e open to browse the HD for image selection The image don t necessarily need to be part of the AHAS project Optionally activate it by pressing the corresponding icon e exit exits image identifier 77 AHAS User Guide Agro ecological indicators View e dentify initiates the slicing procedure Activate
93. s e n case of a load operation the Its file has to be selected using the load Its browser CARE The load operation adds the set to the existing sets already loaded in the AHAS M project AHAS User Guide 82 Agro ecological indicators List of multitemporal images The characteristics of each image selected by the user are display in this list in a tabular form The user can select the column that corresponds to each image to remove from the multitemporal project Sequencing AHAS M arrows The arrows allow the user to shift the order of the selected images in the AHAS M project Usually the selection must be ordered by date of acquisition this tools allows it Select project file in AHAS M The use of AHAS multitemporal or AHAS M that allows the reading of outputs generated in several AHAS projects integrating them temporally according to selected methodologies This dialog box allows the selection of different AHAS projects in order to browse for available input images for the AHAS M procedure Description box Allows the user to enter any description of the data set composed by AHAS individual images Create point map Create Point Map n x Output Name Background Image FEC421 he Y Gi False colour composites OK Cancel T RE Close this process The background image is only used for reference and location See also ILWIS point maps Attribute table for station map Station maps have attri
94. s to color bands Assign Red Green or Blue color to the three selected channels The user can browse in the system by clicking the browse button next to the filename By default Red channel 4 Green channel 2 Blue channel 1 Characteristics of the default configuration e he hottest pixels in the image driest will assume red colors This way is easy to identify sector suffering of stress e Well watered healthy vegetation will assume greenish tones e Blue will indicate less vegetated areas not hot and water bodies Linear stretching Select Linear Stretching if you want to obtain intervals of equal length in terms of input values for the output colors Histogram equalization Select Histogram Equalization if you want to obtain an equal number of pixels for the different output colors Use intervals as Min Max Select this check box to specify input intervals by a minimum and maximum value of each input map Clear this check box to define input intervals by a percentage of pixels to be ignored on both sides of the input map s histogram AHAS User Guide 14 Spectral Composites The intervals of input values If Min Max intervals is checked enter the minimum and maximum values to be considered in each input map If Min Max intervals is not checked enter percentage of pixels to be ignored on both sides of the input map s histogram in each map Normalized difference vegetation index NDVI _ CH2SUR CHISUR N
95. se 2 then select Weighted de mean value in the Option on lt de gt calculator The weight column indicates the proportion decimal of each vegetation structure in the region The weight is a multiplicative factor between O and 1 The user must verify that the summation of the weight column equals 1 3 The user must enter the vegetation structure data height spacing and breadth for each vegetation type selected in the region Each line in the calculator corresponds to one unique vegetation structure The user has to enter all recognizable vegetation types and emissivities before pressing the Apply button 4 The user must enter the emissivity of a pure bare soil and pure vegetation in each selected structure for the spectral range he she wants to work 5 Finally the user Apply the calculation The final de result weighted or averaged depending on the selection is place in the corresponding dialog box ready for further calculations The individual de results are place in the last column scroll to see it Additional features in the de calculator e Each line in the de calculator corresponds to one unique type of vegetation structure that has been identified by the user for the region under study A collection of vegetation structures several lines in the de calculator defines as it best the different types of vegetation structures available in the area This information is distinct for each region and might be
96. ser enters one overall emissivity value for a fully vegetated pixel and one for the fully bare soil pixel 4 The user need to enter the Pv Vegetation proportion map 5 Select a name for the output map and press OK Cases 3 or 4 These options requires the existence of a polygon maps describing the vegetation structure and soil types This last one is optional AHAS User Guide 30 Biophysical Properties 242 Narrow band emissivity ES x Py Vegetation proportion pem sor Input vegetation map mpa 1r Input sol map mpal Vegetation map I Soll map Attribute table Gi d Attribute table m Option on method Option on calculation of de C No vegetation structure map Create ede as an unique value Vegetation structure map Create the de map Show options MIU Specify the output fe Py Vegetation Proportion C Vegetation polygon map Soil polygon map 8 Vegetation structure table 0 Sei info table hd Gol map available Display the selected map e n case the user is in case 3 the option Create lt de gt as one unique value should be selected e n case the user is in case 4 the option Create the de map should be selected e In case a soil polygon map is available the soil map available option should be checked e f the soil map is not available uncheck this option The vegetation str
97. surface flux transfer A LE LE LE H Rn G Acronym A Unit Range Min 1 max 1 precision 20 001 Evaporative Fraction ps xj Input Files Sensible Heat Flux ze E n Instantaneous Total water Use ps SST Output File Bk Close Shaw Histogram T See Help file for the Momentum flux calculator spread sheet Evaporative fraction input All maps required for this output are created in the user interface The required input can be browsed or created from this create dialog box Inputs are e instantaneous latent heat flux map e Instantaneous sensible heat flux map Daily total evaporation ET24 It is the total daily amount of water evaporated from the system System refers here to the soil vegetated land water complex as seen in the processed image Acronym ET24 Unit mm Range Min 0 max 50 precision 0 1 AHAS User Guide 68 Water Characteristics Daily Total Evapotranspiration X Input Files bum Fraction tae ss O i Daily Met Radiation SS IC Output File UR Close Show Histogram e QUT the histogram of the map See Help file for the Momentum flux calculator spread sheet Daily total evaporation input All maps required for this output are created in the user interface The required input can be browsed or created from this create dialog box Inputs are e Evaporative fraction e Total daily ne
98. system and a unique georeference otherwise it will be impossible to operate with them Hardware software requirements Operation system Windows 95 or 98 IL WIS 2 2 software ILWIS home page Minimum Hecommended Processor Pentium Pentium Il or more Internal memory 8 Mb 32 Mb or more HD capacity 1 2 MB 6 MB or more Recommended adds on Excel 97 spreadsheet Internet connection ILWIS software installed in c ILWIS22 directory 7 AHAS User Guide Introduction to AHAS Installation Download file AHAS zip and uncompress it in a temporal folder Run the setup exe program The installing program will setup AHAS program on your Windows PC After the installation a file named AHAS ini is installed in your Windows directory where paths for running ILWIS2 2 and AHAS exe are defined By default the application will be installed in c program files ahas Uninstallation To uninstall AHAS program select Add Remove Program from settings Control Panel from the Start menu AHAS User Guide 8 Introduction to AHAS Starting AHAS 1 Click Programs AHAS AHAS from the Start menu Then you will see the main application window and the project window 2 From AHAS File menu in the AHAS application window select Open New Project In the dialog that appears navigate to the location of the directory that contains the project or create a new one An example is located in c rbsp image set3 Click project1 and then press ok button When
99. t radiation Volumetric soil water content It is the ratio of water volume to soil volume Acronym 6 Unit mm mm Range Min 0 max 1 precision 0 01 Soil Moisture Classes A X Input Files evn Fraction Cae BF te Output Fie Conversion Factor o oS D ci 1 2035 o2 0 4213 OF Close Show Histogram T ux Diaplay the histogram of the map Volumetric soil water content input All maps required for this output are created in the user interface The required input can be browsed or created from this create dialog box Inputs are e evaporative fraction map The proposed equation to derived volumetric soil water content as described in the FIFE and EDEDA data is 69 AHAS User Guide Agro ecological indicators A 0 a C5 where A is the evaporative fraction c constant Default 1 2836 Go constant Default 0 4213 AHAS User Guide 70 Agro ecological indicators Agro ecological indicators Photosynthetical Active Radiation PAR It is the part of the short wave solar radiation 0 3 to 3 0 um that supports the photosynthesis in green plants Acronym PAH Unit watt m Range Min 0 max 1000 precision 20 01 Photosynthetical Active Radiation ES Input Files Deco Shortwave Solar Radiation KinDay me Ex O Output File Conversion Factor ci 10 48 OF Close Show Histogram
100. table conditions m and for heat subindex bi 0 25 dE lt a J lm MOI 0 25 d Lie iie iet Ol M g Follows the calculation of the Integrated non dimensional Monin Obhukhov stability correction factor for heat yii 1 y Pa e d al h Now the friction velocity can be corrected by buoyancy effects 0 41 u avg where l Zin i Resulting in the second estimate of the aerodynamic resistance to heat transport fano i In Es GH py 0 41 u j After this routine the procedure starts all over again using the new estimate of the aerodynamic resistance to heat transport rau to obtain new values for constants a and b resulting in an improved estimate of the near surface temperature difference relation ATa and Ln AHAS User Guide 62 Climatic Characteristics in turn in an improved version of the sensible heat flux H AT Rn G Jr b where AT Mo Gay Ta 2 an a Doan cub d Pa i Cp a D P us ATa a b T H if ATa 0 p c ATa rn DU k This process should continue until no changes in the sensible heat flux map are determined anymore Building in a certain threshold value below which the process is stopped In this case only the next step is shown following L u poc Ua T vw 4002 H an A 2m Je MO2 SC Xan EE d MO2 1 4 y m where ls 1 y 0 41 ty Za d 2 Y Som ES dl EI 0 01 7 Pn
101. tandard meridians slices of 15 being Greenwich the zero meridian Countries adopt one or more standard meridians The user can obtain the corresponding standard meridian from a time zone map The user can select the standard meridian from a drop down list e DST some countries use daytime saving time scheme The main purpose of Daylight Saving Time called Summer Time many places in the world is to make better use of daylight Daylight Saving Time makes the sun set one hour later and therefore reduces the period between sunset and bedtime by one hour By checking this option the user indicates that the local time entered is DST Note The procedure programmed in AHAS for the estimation of the solar zenith angle does not consider the different timing that corresponds to the readings of the pixels in the image It assumes that the entire image was acquire in a certain instant entered by the user This assumption introduces an error in the final solar zenith angle map but because of its small magnitude it is not expexcted to affect outputs using this map AVHRR pre processing software uses orbital models to calculate the reading time for each pixel producing more accurate SZA maps Use the output from this software for more accurate results in AHAS File amp cursor info The file area shows information on the image attributes When navigating with the cursor over the image the description status area displays the current row and column
102. te table This data will be used to create the first friction velocity map The data might be available in some of the stations only but the user is able to add more stations and data at any time The data required is e Wind speed meter second officially at the moment the satellite passed u This is variable for each station e The height m where over ground level where the wind speed was measured z This is variable for each station e he station altitude over sea level m This is variable for each station Other information e The altitude of the blending height z in meters default 100 m This is considered fixed for the entire map e he air specific heat at constant pressure c Joules kg KL Requested to be entered by the user default 1004 16 e The height reference at which momentum fluxes apply is called z m This value has to be decided by the user Default 5 m Important e Before offering this value as default the user interface checks that none of the pixels in the zero height displacement map d has a value bigger than 5 m If this happens the default value is changed to max d 1 meaning the maximum value in the d map 1 e he user is able to change the default to another value After the change the user interface checks this condition and warns the user about the existence of d values higher or equal to the z selected by the user In this case the interface allows the user to revie
103. the create column table button to create the columns requires for the process The attribute table will open and the user is ready to enter values e The user has to enter the following data per station underlined if data is compulsory uz wind speed m s at the moment the image was taken zz height at which the wind speed was measured m Alt the altitude of the station over sea level m Po air pressure at the station in the moment of the measurement milibar This is optional otherwise the pressure is calculated from the altitude e T and Tao air temperature at the stations at the moment the image was taken C Tao refers to air temperature at the stations with barometers e RH relative humidity 9o at the moment the image was taken Pixel values on To The system automatically will retrieve from the shown temperature map the value of the pixels having the maximum and minimum temperature They will be considered the default driest and wettest pixel in the image It is essential to process a cloud free image to accept these values as default Pixel Coordinates The system will retrieve the file coordinates for these defaults The user might want to explore the validity of these values Using the show and histogram functions over the available maps can do this In case the user decides not to accept the defaults for wettest and driest he must enter the new coordinate values for these pixels in the corresponding fie
104. the air temperature at the station with barometers K Il If there is not any station having air pressure then we will assume that air pressure at sea level is equal to 1013 millibars and use the altitude to correct for the pressure 5 25864 T 1 P 1013 L T 0 0065 alt Tun where alt is the altitude over sea level m of station 1 The final pressure is calculated for the stations priority order a b c e A virtual temperature T Kelvin column is calculated per station 17 27 T 2773 e 6 108 exp E ELA T_ 273 2313 RH eg 7 ls 100 Then AHAS User Guide 60 Climatic Characteristics Ed Ti T a 0 378 a 1 and finally P 0 3486 p kv Gu is the is the water vapor pressure in millibars e is the saturated water vapor pressure millibars RH is the relative humidity at the station 96 T is the screen air temperature in K All these values are measured at the station for which p is calculated The final map p is calculated as point interpolation for the station User decision and user interface support At this point the user has to interfere to be able to continue with the algorithm n fact this part is the heart of the methodology and the interaction will have a major influence on the final results The user has to instruct the system by selecting the driest and the wettest pixel in the image The posit
105. this function after all intervals have been defined Optionally activate it by pressing the corresponding icon e Histogram display the histogram of the current image to assist the interval selection Optionally activate it by pressing the corresponding icon e Clear clears the graphic sliced classification Optionally activate it by pressing the corresponding icon e Refresh refreshes de classification Use this option when the graphical representation is distorted by any reason Options Sheet operations e Add a line to add a new line for a new interval click the the table pivot upper left square named as add or select this option from the menu e Delete a line Delete a line classification interval Click on any cell of the line to delete and then select this option Slicing table From here the user can e Add a new interval or edit an entered one click once in any place of the line A dialog box appears allowing the user to select the interval range and a color representation for this range e Add a new interval line to add a new line for a new interval click the the table pivot upper left square named Add e Delete an interval Delete a line classification interval Click on any cell of the line to delete and then select option sheet operations delete a line Solar zenith angle map The solar zenith is the angle between a projected line from a certain terrestrial location pixel location to the zenith and othe
106. tion Column transmittance invisible The column contains the ratio between the incoming solar radiation at the ground previous column and the extracted value of the corresponding pixel in the map instantaneous hemispherical SW radiation map b e The station point map is interpolated by the attribute column transmittance invisible to create the one way transmittance map x temporal in the system The user must verify the interpolation method prior to calculations It is advisable the moving average inverse for this case e The user closes the table selects a name for the output and click OK for the calculations Instantaneous outgoing longwave radiation LT It is the thermal energy range 3 100 um emitted by Earth surface to the atmosphere in a certain specific moment Acronym LT Unit watt m Range Min 0 max 1000 precision 0 1 Instantaneous Dutcoming Longwave Radiation X Input Files Surface Temperature M ap price Cae ae O Broadband Emissivity Map Jeo Ex ule Dutot File EE DE Close Show Histograrn P Display map Instantaneous outgoing longwave radiation input The input required for the calculation of this map are e he broadband emissivity map e he instantaneous incoming Longwave radiation map e he surface temperature map All maps must exist in the project The user could browse to find the maps in the system The user must select one available map per input i e th
107. tional calculation of the exact value of de is rather complicated The user interface has to produce a series of calculations in order to produce a unique value of de l The UI calculates the G F and F values in the attribute table from the vegetation map IH A Pt column can be calculated from the attribute table from the vegetation map I Pt S L Il H L S G F F and Pt attributes from the vegetation map are rasterized using the georeference in the system IV attribute from the vegetation map is rasterized using the georeference in the system V g attribute from the soil map is rasterized using the georeference in the system VI VII A Ps map is created as _ H L tan VZA S VIII A de map is calculated as 27 AHAS User Guide Biophysical Properties So a simplified method is proposed in this UI l The UI calculates the F value in the attribute table from the vegetation map l A Pt column can also be calculated from the attribute table from the vegetation map I Sen Il The Pt and F from the attribute table of the polygon map is rasterized using the georeference in the system Pt IV e attribute from the soil map is rasterized using the georeference in the system V The de raster map is calculated as lt de gt 1 F 1 Pt VI The average value of this map is de and is used for further calculations the calculations The user is in case 4 In t
108. ttributes meteo data of different kind for each station The user is able to edit the meteodata point map and add remove meteostations See ILWIS help file ILWIS point maps e Once the station is entered or selected select a name edit the attribute table open attribute table show button The user is then requested to enter the value of the incoming solar radiation at the ground column Kin i in watt m at the moment the image was taken in the station This information is stored in a column of the station point map attribute table e Based on this point map attribute table via scripts another temporal column is created without user interaction Column transmittance The column contains the ratio between the incoming solar radiation at the ground previous column and the extracted value of the corresponding pixel in the map instantaneous hemispherical SW radiation map b e The station point map is interpolated by the attribute column transmittance invisible to create the one way transmittance map x Moving average inverse distance is the default interpolation method To select other method see interpolation options e The cg map is the one way transmittance map at the power 2 Cg T e f the user enter the available stations but solarimeter data is unavailable for one or more enter the undefined character in the corresponding column 4 The ry map is produced automatically since all data is now available 23 AHAS Us
109. ucts that can be derived from only one image One sensible way to offer multi temporal analysis from outputs created from AHAS is the use of AHAS multitemporal or AHAS M that is able to read outputs generated in AHAS integrating them temporally according to the methodologies explained below AHAS M is integrated with AHAS and certainly is able to manage outputs from different AHAS projects Time E HAS Project me AU Project 3 AHAS M Project AHAS Project 2 AHAS Project 1 Space It can also be seen as described in the previous graph A single AHAS project covers a certain portion of space the same in this case at a certain time A single AHAS M project integrates in time several AHAS projects having the same spatial coverage Each AHAS project will be assumed to occur during a certain time t then the gt t covers the total time assigned to an AHAS M project AHAS User Guide 72 Agro ecological indicators The user through the AHAS M interface controls the duration of each tl Each AHAS M output is unique for a certain space and certain temporal coverage Accumulated APAR AcAPAR Definition It is the energy absorbed by the canopy that was used for carbon dioxide assimilation ACAPAR is then a measure for the accumulation of APAR with time This is an AHAS M product Acronym AcAPAR Unit MegaJoules m Range Min 0 max 30000 precision 1 AHAS M Select a project file Ebert Load
110. ucture map The vegetation structure is a reclassification from a vegetation map in most of the cases If no vegetation map is available or no information of vegetation structure classes is available then the user is in cases 1 or 2 The vegetation map is a polygon file describing the spatial distribution of the main types of vegetation The vegetation structure is described in an attribute table of the vegetation map The attribute table contains four attribute columns plus the link to the polygon map e column ev Vegetation emissivity e column height vegetation height H meters column spacing vegetation separation S meters column breadth vegetation breadth L meters There might be other column created by the system eg The user has to fill this column only in the case that there is not soil map available See below The soil emissivity map A The soil type polygon file is available The user has to reclassify the soil map into an soil emissivity map for the spectral range under consideration Then the soil polygon map is needed together with its attribute table containing one column eg for e for each soil unit B The soil type polygon file is unavailable If the soil map does not exist then the Ul assumes that each vegetation type is located in a certain soil type Then the soil map shape is identical to the vegetation map The user interface will reclassify the vegetation map into the emissivity map Only in th
111. uired Care the equation is an approximation It is only accurate in case of Sea surface temperature C 0 39 22 94 C075 UNE E Goo 0 99 Offset 0 56 Price 1984 C452 0 Cy 4 33 5 5 4 4 5 Lee 0 Cs 3 33 5 5 4 4 5 0 75 Ag Lass 0 Offset 0 Required maps Emissivity in channel 4 and 5 Required procedure Calculate AVE and DE maps by pressing the correspondent buttons before the final calculations AHAS User Guide 34 Create Surface Temperature 2 x Input Files fr mor T4 Brightness Temperature for Channel 4 Channels Gel T5 Brightness Temperature for Channel 5 Channels Gel Coefficients Used to Generate Surface Temperature Map C42 0 33 C4 2 34 C45 0 78 C5 1 34 C52 0 39 Offset 0 56 TU c42 CHA4BT CHABT cA CHABT c45 CH5BT CHABT c5 CHBBT c52 CH5BT CHB5BT offset ssT Coll and Caselles 1997 v Show C Channel 5 DK Close Show Histogram 9 Create Surface Temperature X Input Files 1 mon T4 Brightness Temperature for Channel 4 Channel T5 Brightness Temperature for Channel 5 Channels Coefficients Used to Generate Surface Temperature Map C42 0 AVE E4 E5 2 C4 4 33 5 5 E4 4 5 DE E4 E5 C45 0 C5 3 33 5 5 E 4 4 5 0 75 DE C52 0 Offset 0 E4 Emissivity map in channel 4 E5 Emissivity map in channel 5 Methods ta generate surface temperatu
112. umber of distinct structures The user interface provides some assistance to the user e Links to global vegetation maps or other useful pages in internet in order to define main vegetation structures e A database for soil and vegetation emissivities in channel 4 and 5 to define narrow band emissivity values for pure classes e A de calculator this is an specialized calculator that provides the value of de based on certain parameters entered by the user e Finally the user enters in the system an unique value of de equal to the average of all lt de gt s he investigated lt de gt d Avg de Where de is calculated by each vegetation structure The user is in case 2 In this case the de term is only one unique value entered by the user The user can apply the same tools available for the case 1 but the final de is a weighted mean value The equation he might use is de gt de gt f de i Where de is calculated by each vegetation structure fi is the weight area corresponding to each vegetation unit The user counts with an on line calculator for de estimates the weighted de has to be calculated outside and is enter manually The user is in case 3 In this case the lt de gt term is only one unique value calculated from GIS techniques through the user interface The user provides e The vegetation map and attributes data e The soil map and attributes data The opera
113. ust be given See Interaction with the user interface in the surface roughness parameter AHAS User Guide 40 Biophysical Properties Surface roughness for momentum transport Zo It is a fraction of the crop height used as a physical reference for momentum and heat flux z calculations For an open site the wind profile can be described for a logarithmic law u z A In z B B is usually replaced by A In zo where ze is a small value of z for which the previous d zo equation predicts u z 0 Then dp u z A In z zo Zo is called aerodynamic roughness of the surface Wind Profile US Acronym zo Unit meter Range Min 20 max 0 2 precision 0 00001 Surface Houghness E x Input Images DE Leaf Area Indes Map lai r4 aor Close Vegetation Height M ap SZ e Coefficient Used to Create Surface Roughness Map gt Unobstructed Bare Soil Drag Row crop and tiger bush 0 003 sl Overstores Drag coefficient 0 35 Constant Cw E Output File Hun to Create Leaf Area Index Map See displacement height d Surface roughness input The basic input for the roughness length for momentum transport as described in the roughness length theory is three maps e LAI e The vegetation height map e The displacement height map The UI allows an extreme simplification if a vegetation height map h is unknown The map could be replaced by a constant representin
114. w the value or accept the errors that will happen as undefined values in the final maps Processing initial data Initial conditions and simplified hypothesis a From these data a new column u in the attribute table must be created in order to evaluate wind speed at the blending height Z in metres Transforming wind speed at z to the user selected blending height z In z d Inz Wy ER In d Inz where Uug is the wind speed meters sec at the station at the blending height z height meter u is the wind speed meters sec measured at the station at a high z meters d is the zero height displacement value of the pixel where the station is located m Zom IS the surface roughness value of the pixel where the station is located m b The value of the wind speed map at the blending height can be created by averaging the wind speed uy m s at z meters This is a constant for the entire image We call it Upayg At blending height roughness effects are negligible and wind speed might be considered areally constant C First estimation of the friction velocity u from ground data measurements This map is to be changed during the iteration process The first approach is done by assuming a wind profile under neutral conditions See momentum flux theory 59 AHAS User Guide Climatic Characteristics where d is the height displacement map metres d Due to uncertainties in the Z Z r
115. xels Interpolation options Some procedures in the user interface require the interpolation from ground point data ILWIS offers several interpolation procedures For the user interface we adopted only two simple methods which might be enough for the case of simple interpolation of selected meteorological and hydrological variables Point interpolation Nearest point Point interpolation Moving average 81 AHAS User Guide Agro ecological indicators The interpolation method must be selected before the calculation takes place The UI assigns default interpolation options for different outputs that must be verified controlled by the user There are 2 ways to access the interpolation options 1 An interpolation button in the create dialog box of the corresponding output A button is visible when the output map does not change dramatically when is calculated with different interpolation methods It is not visible when the default interpolation option is advisable however the interpolation parameters must be checked 2 From the main menu Tools interpolation options Status help area The area at the button of the dialog box is reserved to display some context or help information related with the current position of the cursor Create column button se This button is available in the create dialog box of variables requiring information from ground stations to be entered by the user The user must set all the required maps an

AHAS (AVHRR Hydrological Analysis System)

Contents

Download Pdf Manuals

Related Search

Related Contents