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L2 RMIB GERB Products User Guide - NCEO

1. 55 4 3 How to Obtain the HDF5 Library oaaae 55 AA Overview of HDES a a A A tae ee ease a po Ga a a O 55 AAT Objects maa aaa amp be Rh eae A a o da We A 55 44 2 Hierarchical Layout veses gh gi gorte ee Se i e a aa e dida e e 56 LAS AP eepe a J e tage dew Be de AS DDN SS A td A 56 AAA Lite AP a A ye ek sd a o ie eS 57 4 5 How to Retrieve HDF Data 02 0 2 ee ee ee 57 A A AN 57 4 5 2 Dataset ACCESE iii A he ak oa ler Dedo 57 49 37 AttributecAc ess e n a o o OS ED ee eae de de eel 58 L04 Data TYp s rua ke en Re Oe ee ee ee at he ee 59 4 55 Example on ten e A 22 2a eee at a Edw ewe eA 60 4 6 HDF Tools Provided by NCSA 2 2 2 0 00002 ee a 63 A Sample Code 66 AL Float mace noc alada 3 43 5 ds de a does ot Bg abusers a eB ed 66 A2 Integer Image n a 22 2 Set es Bee eee he BSB REE EL SA eae 2 67 ALS UString Data pare we ee A eee A A ee a eee Bed 69 Ad Strine ists asta REE EN SS ee ee ld e 70 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 List of Tables 1 L2 RMIB GERB Products e 10 2 Hierarchical structure of the product L20L o 10 3 Hierarchical structure of the product L209 o o 11 4 Hierarchical structure of the product L20 0000 13 5 Hierarchical structure of the product L20L_H_EUROPE 13 6 Hierarchical structure of the product
2. 3 74 Cloud Phase Dataset Description This dataset contains the mean cloud phase water or ice cloud over the foot print A cloud phase of O corresponds to a pure water cloud A cloud phase of 100 corresponds to a pure ice cloud And between this limits mixed water ice cloud 49 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 HDF Path Scene Identification Cloud Phase Additional Information Data type H5T_STD_U8BE Error Value 255 Range 0 100 water 0 mixed ice 100 3 75 Solar Angular Dependency Model Dataset Description This dataset contains the identifier of the scene type dependent Angular Dependency Model that has been used to convert the reflected solar radiance in the reflected solar flux HDF Path Scene Identification Solar Angular Dependency Model Additional Information Data type H5T_STD_U8BE Error Value 32367 Range 0 1024 3 76 Surface Type Dataset Description This dataset contains the surface type within the GERB footprint or grid cell The defined types are 0 undefined 1 ocean dark vegetation bright vegetation dark desert bright desert snow HDF Path Scene Identification Surface Type Additional Information Data type H5T_STD_U8BE Allowed values 0 undefined 1 ocean 2 dark vegetation 3 bright veg etation 4 dark desert 5 bright desert 6 snow 255 error 50 Royal Meteorological Institute MSG RMIB GE
3. HDF Path Times Start of Integration Additional Information Data type H5T_C_S1 The format is YY YYMMDD HH MM ss 3 85 End of Integration per column Dataset Description The end of integration parameter gives the time of end of integration for every image column The imager data is not considered only time of GERB data used for column data generation is taken into account HDF Path Times End of Integration per column Additional Information Data type H5T_C_S1 The format is YYYYMMDD HH MM SS MMM 53 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 86 Start of Integration per column Dataset Description The start of integration parameter gives the time of start of integration for every image column The imager data is not considered only time of GERB data used for column data generation is taken into account HDF Path Times Start of Integration per column Additional Information Data type H5T_C_S1 The format is YYYYMMDD HH MM SS MMM 3 87 Time per row Dataset Description This dataset contains the acquisition time for every image row HDF Path Times Time per row Additional Information Data type H5T_C_S1 The format is YYYYMMDD HH MM SS MMM 54 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 4 L2 RMIB GERB Products Data Access 4 1 Introduction The L2 RMI
4. herr_t H5LTread_dataset_uchar hid_t loc_id const char dset_name char data hid_t dataset_id Open the dataset if dataset_id H5Dopen loc_id dset_name lt 0 return 1 Read if H5Dread dataset_id H5T_NATIVE_UCHAR H5S_ALL H5S_ALL H5P_DEFAULT data lt 0 goto out End access to the dataset and release resources used by it if H5Dclose dataset_id return 1 return 0 out H5Dclose dataset_id return 1 68 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 A 3 String Data The following code shows how to retrieve the value of a string attribute The source code file name is read_rgp_string c ttinclude lt stdio h gt ttinclude lt stdlib h gt HDF5 Library header file include lt hdf5 h gt include lt H5LT h gt The assert macro is used to detect any error and exit from the program in case something went wrong ttinclude lt assert h gt int main int argc char argv char file_name hid_t file_id herr_t error char attr_string_value NULL size_t attr_string_size H5T_class_t type_class The argument on the command line is the name of an HDF file which must contain a File Creation Time string attribute assert argc 2 filename argv 1 Open the HDF file file_id H5Fopen filename H5F_ACC_RDONLY H5P_DEFAULT asser
5. GGSPS L1 5 NANRG Product Version Geolocation Geolocation Geolocation File Name Geolocation Line of Sight North South Speed Geolocation Rectified Grid Geolocation Rectified Grid Grid Orientation Geolocation Rectified Grid Lap Geolocation Rectified Grid Lop Geolocation Rectified Grid Nr Geolocation Rectified Grid Nx Geolocation Rectified Grid Ny Geolocation Rectified Grid Xp Geolocation Rectified Grid Yp Geolocation Rectified Grid dx Geolocation Rectified Grid dy Geolocation Rectified Grid Resolution Flags Geolocation Rectified Grid Resolution Flags East West Geolocation Rectified Grid Resolution Flags North South Geolocation Nominal Satellite Longitude PSF Parameters Imager Imager Instrument Identifier Imager Type RMIB RMIB Software Identifier RMIB Product Version Radiometry Radiometry Longwave Correction Radiometry Resolution Enhancement Parameters Radiometry Spectral Regression Parameters Radiometry Thermal Radiance Radiometry Thermal Flux Radiometry A Values per GERB detector cell Radiometry C Values per GERB detector cell Scene Identification 25 25 25 27 26 28 28 28 29 29 29 32 32 32 33 33 33 33 34 34 34 35 35 35 35 36 36 36 45 41 41 41 41 42 42 42 43 45 46 47 47 47 48 48 Scene Identification Thermal Angular Dependency Models Set Version 51 Times Times End of Integration Times Start of Integration 52 52 5
6. Geolocation Geolocation File Name Additional Information Data type H5T_C_S1 3 21 Line of Sight North South Speed Attribute Description The angular speed in north south direction of the GERB line of sight during the earth view HDF Path Geolocation Line of Sight North South Speed Additional Information Units Degree per second Data type H5T_IEEE_F64BE This line of sight speed influences the dynamic point spread function of the GERB instrument 3 22 Rectified Grid Group Description This group contains the parameters that describe the rectified grid on which the GERB observation points are located The rectified grid is the grid obtained by an equi angular projection from a geostationary satellite as shown in figure 2 HDF Path Geolocation Rectified Grid Additional Information None 32 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 23 Grid Orientation Attribute Description The angle between the increasing y axis and the meridian of the sub satellite point in the direction of increasing latitude HDF Path Geolocation Rectified Grid Grid Orientation Additional Information Units Millidegree Data type H5T_IEEE_F64BE 3 24 Lap Attribute Description Latitude of sub satellite point HDF Path Geolocation Rectified Grid Lap Additional Information Units Degree Data type H5T_IEEE_F64BE 3 25 Lop Attribute D
7. L Gonzalez introduction of MSG7 as possible imager 25 11 2002 L Gonzalez addition of Summary Thermal Products Confidence Summary Solar Products Con fidence Radiometry Longwave Correc tion Minimum Correction Value Radiom etry Shortwave Correction Minimum Correc tion Value Radiometry Longwave Cor rection Maximum Correction Value Ra diometry Shortwave Correction Maximum Correction Value 25 11 2002 L Gonzalez Mapped range has been splitted on Range and Offset 25 11 2002 L Gonzalez Surface Type has been modified ACRONYMS API Application Programming Interface ARG Averaged Rectified Geolocated BARG Binned Averaged Rectified Geolocated FTP File Transfer Protocol GERB Geostationary Earth Radiation Budget HDF Hierarchical Data Format HTTP Hypertext Transfer Protocol L1 5 Level 1 5 L2 Level 2 MSG Meteosat Second Generation NANRG Non Averaged Non Rectified Geolocated NCSA National Center for Super Computing Applications RAL Rutherford Appleton Laboratory RMIB Royal Meteorological Institute of Belgium ROLSS RMIB On Line Short Term Services SEVIRI Spinning Enhanced Visible and Infrared Imager SHI Snapshot High Resolution Image WWW World Wide Web Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 1 Purpose of this Document This guide is intended to assist users of the Level 2 L2 products derived from the Geost
8. L20S_H_EUROPE 14 7 Hierarchical structure of the product L2Q0G_H_EUROPE 16 8 Hierarchical structure of the product L20L_15M_50 16 9 Hierarchical structure of the product L20S_15M_50 17 10 Hierarchical structure of the product L20G_15M_50 19 11 Hierarchical structure of the product L20A_H o 19 12 Hierarchical structure of the product L20G_H 00 21 List of Figures 1 Sun target satellite geometry 26 2 Geolocationice sos re doi rte A hee ie a Oe ee 8 30 3 Geodetic geocentric radang aa aa a e a ag aan an aa a aa a a e 31 4 Output of command read_demo_file aaa aaa a 64 5 Output of command h5ls r demo hdf 64 6 Output of command h5dump demo hdf oaa o 65 Royal Meteorological Institute of Belgium MSG RMIB GE UG GERB Version 1 2 CHANGE RECORD Issue Date Changed by Reason for change Version 1 07 6 2000 New document Version 1 1 08 9 2000 G Sadowski Corrections and additions following the rec ommendations of the review board 4 Review 06 9 2000 Version 1 2 03 6 2002 L Gonzalez Radiance and flux on same file except for ARG 25 11 2002 L Gonzalez Rewriting of chapter L2 RMIB GERB Prod ucts Data Acess using HDF5 Lite API 25 11 2002
9. This section presents the listing of an example C program that will read the HDF file demo hdf provided with this guide The code shows how to use the functions of the HDF5 API discussed in the preceding sections Namely it demonstrates how an application can open an HDF file and access its groups datasets and attributes The file read_demo_file c contains the source code of the example To compile it you should have the HDF5 Library installed see section 4 3 Please refer also to appendix A for additional examples There are two versions of the same data extraction in this file one using dynamic allocation of memory and the other using static arrays Using only static arrays can lead to memory availability problems 60 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 ttinclude lt stdio h gt ttinclude lt stdlib h gt include lt string h gt HDF5 Library header file include lt hdf5 h gt include lt H5LT h gt The assert macro is used to exit from the program in case something went wrong include lt assert h gt define DIM_0 20 define DIM_1 10 int main void Name of the HDF file char file_name demo hdf IDs for accessing HDF5 objects hid_t f_id Will contain information about the dataset number of dimensions number of data points dimensions sizes int num_dims hsize_t num_points dims Will contain the s
10. 3 1 Summary Thermal Products Confidence Attribute o 3 2 Summary Solar Products Confidence Attribute o o 3 3 Duplication Flag Attribute e e 3 4 File Creation Time Attribute 2 2 0 2 0 2 0 0 a 3 0 FileName Attribttte s eD ariii a aoa E E a a ae eee 3 6 Radiation Type Identifier Attribute 2 2 o oo o 3 1 Angles Group te a 2 64 bb beud A e e ee SS S466 F444 0 84 doe 4 3 8 Relative Azimuth Dataset ee ee ee 3 9 Viewing Azimuth Dataset ee ee 3 10 Solar Zenith Dataset voir VANS S DDO ESE RA a es sll Viewing Zenith Dataset eraa p 222444400 eB ee Go a al ala be 3 12 GERB Group se once a fa DAS RS OS ea ha did a 3 13 Instrument Identifier Attribute e 3 14 GGSPS Group s a a ed A ee ae l 3 15 L1 5 NANRG File Name Dataset gt o saaan o e e 3 16 L1 5 NANRG Product Version Dataset o e 3 17 Geolocation Group ese ee we a a ad da i a 3 18 Latitude Dataset oc mewa u a AAA A aa eS 3 19 Longitude Dataset s e e 3 20 Geolocation File Name Attribute 2 2 0 2 0 o o 3 21 Line of Sight North South Speed Attribute o o e 3 22 Rectified Grid Group vr a ee eae aaa ea 3 23 Grid Orientation Attribute o e a 3 24 Lap Attribute 2 inicia a a A a 3 207
11. 41 RMIB 41 RMIB Software Identifier 42 RMIB Product Version 42 Radiometry 42 Radiometry Longwave Correction 43 Radiometry Spectral Regression Parameters 46 Radiometry Thermal Flux AT Radiometry Thermal Radiance AT Radiometry A Values per GERB detector cell AT Radiometry C Values per GERB detector cell 48 Scene Identification 48 Scene Identification Thermal Angular Dependency Models Set Version 51 Times 52 Times First GERB Packet 52 Times Last GERB Packet 53 Times End of Integration per column 53 Times Start of Integration per column 54 2 3 2 lt GERB_ID gt _ lt IMAGER_ID gt _L20S_ lt DATE gt _ lt VERSION gt hdf This is an ARG product This product contains solar fluxes and unfiltered radiances for distribution by the GGSPS defined to be compatible with the GERB filtered radiances derived by the GGSPS Table 3 Hierarchical structure of the product L209 Access Path Name Page Summary Solar Products Confidence 24 Duplication Flag 24 File Creation Time 25 File Name 25 Radiation Type Identifier 25 GERB 28 GERB Instrument Identifier 28 GGSPS 28 GGSPS L1 5 NANRG File Name 29 GGSPS L1 5 NANRG Product Version 29 Geolocation 29 continued on next page 11 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 continued from previous page Geolocation Geolocation File Name 32 Geolocation Line
12. 60 70 80 90 100 11 22 33 44 55 66 77 88 99 110 12 24 36 48 60 72 84 96 108 120 13 26 39 52 65 78 91 104 117 130 14 28 42 56 70 84 98 112 126 140 15 30 45 60 75 90 105 120 135 150 16 32 48 64 80 96 112 128 144 160 17 34 51 68 85 102 119 136 153 170 18 36 54 72 90 108 126 144 162 180 19 38 57 76 95 114 133 152 171 190 20 40 60 80 100 120 140 160 180 200 3 1415926535897931 This string is the value of the attribute Figure 4 Output of command read_demo_file demo hdf First Group Group demo hdf First Group My Dataset Dataset 20 10 Figure 5 Output of command hbls r demo hdf 64 Royal Meteorological Institute of Belgium GERB MSG RMIB GE UG Version 1 2 HDF5 demo hd 4 GROUP GROUP First Group DATASET My Dataset DATATYPE H5T_STD_I32BE DATASPACE SIMPLE 20 10 20 10 gt DATA pb 2 3 4 5 6 7 8 9 10 4 6 8 10 12 14 16 18 20 6 9 12 15 18 21 24 27 30 8 12 16 20 24 28 32 36 40 10 15 20 25 30 35 40 45 50 12 18 24 30 36 42 48 54 60 14 21 28 35 42 49 56 63 70 16 24 32 40 48 56 64 72 80 18 27 36 45 54 63 72 81 90 10 20 30 40 50 60 70 80 90 100 11 22 33 44 55 66 77 88 99 110 12 24 36 48 60 72 84 96 108 120 13 26 39 52 65 78 91 104 117 130 14 28 42 56 70 84 98 112 126 140 15 30 45 60 75 90 105 120 135 150 16 32 48 64 80 96 1
13. 69 A Values per GERB detector cell Dataset 0 o 47 3 70 C Values per GERB detector cell Dataset o o e 0 o o 48 3 71 Scene Identification Group ee 48 3 72 Cloud Amount Dataset iii a a a e e e ee 49 3 13 Cloud Cover Dataset ies a da a 49 3 14 Cloud Phase Dataset lt c 2 44 24 o se hae ee ee eee PG ee Oe 49 3 75 Solar Angular Dependency Model Dataset o o o o o 50 3 16 Surface Type Dataset oi es 2 5 3 4 ra A A a 50 3 77 Thermal Angular Dependency Model Dataset o oo o 51 3 78 Solar Angular Dependency Models Set Version Attribute 51 3 79 Thermal Angular Dependency Models Set Version Attribute 51 3 80 Times Group os vi dd aa aA a aa pd A a E 52 3 81 End of Integration Attribute ooa en 52 3 82 First GERB Packet Attribute 2 2 2 2 ee ee eee 52 3 83 Last GERB Packet Attribute o oaa en 53 3 84 Start of Integration Attribute o a 53 3 85 End of Integration per column Dataset o oo a o 53 3 86 Start of Integration per column Dataset oa o a oo 000005 54 3 87 Lime pertow Dataset sots go m a t doi daa Pee Ea GS Mies Aa i 54 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 4 L2 RMIB GERB Products Data Access 55 AA Introduction s re eom e e A a e 55 4 2 How to Obtain the L2 RMIB GERB Products
14. Description This information in this group is copied from the level 1 5 Non Averaged Non Rectified Geolocated NANRG GERB radiance product that has been used as input file It contains information about the GGSPS software that was used to produce this NANRG product 28 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 HDF Path GGSPS Additional Information See GGSPS documentation 3 15 L1 5 NANRG File Name Dataset Description The name of the L1 5 NANRG files that have been used as input The name of the main file is the first item HDF Path GGSPS L1 5 NANRG File Name Additional Information Data type H5T_C_S1 See L1 5 NANRG documentation for more details 3 16 L1 5 NANRG Product Version Dataset Description The product version of the L1 5 NANRG files that have been used as input The version of the main file is the first item HDF Path GGSPS L1 5 NANRG Product Version Additional Information Data type H5T_STD_I32BE See L1 5 NANRG documentation for more details 3 17 Geolocation Group Description This group contains the parameters that describe the location on earth for the GERB observations The location is given in geodetic coordinates relative to the earth reference ellipsoid HDF Path Geolocation 29 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Additional Information The geolocation parameters for
15. Institute MSG RMIB GE UG of Belgium GERB Version 1 2 The necessary functions for retrieving data from an existing HDF file are explained in section 4 5 Note that we only present the subset of the API needed to extract the information stored in the RMIB GERB flux products files For a complete coverage of the HDF5 library please refer to the full NCSA documentation see 4 3 4 4 4 Lite API The HDF5 Lite API consists of higher level functions which do more operations per call than the basic HDF5 interface The purpose is to wrap intuitive functions around certain sets of features in the existing APIs This version of the API has two sets of functions dataset and attribute related functions These functions hide most of the API complexity 4 5 How to Retrieve HDF Data In order to retrieve the data stored in an HDF file a program needs to gain access to the object containing these data The basic usage scheme corresponds to the execution of the following steps 1 Open the file 2 Read the value s stored in the object 3 Close the file The functions that perform these operations are explained in the following sections 4 5 1 File Access To access the content of an existing file the file must first be opened with a call to the function H5Fopen hid_t H5Fopen const char name unsigned flag hid_t access_properties where name is the name of the file to open and flag describes the type of ac cess H5F_ACC_RDONLY f
16. Latitude 30 Geolocation Longitude 31 Geolocation Rectified Grid 32 Geolocation Rectified Grid Grid Orientation 33 Geolocation Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South 36 RMIB 41 RMIB Software Identifier 42 RMIB Product Version 42 Times 52 Times First GERB Packet 52 2 3 7 lt GERB_ID gt _ lt IMAGER_ID gt _L20L_15M_50_ lt DATE gt _ lt VERSION gt hdf This is a BARG product This product contains thermal radiances and fluxes defined for easy comparison with model output Table 8 Hierarchical structure of the product L20L_15M_50 Access Path Name Page Summary Thermal Products Confidence 24 Duplication Flag 24 File Creation Time 25 continued on next page 16 Royal Meteorological Institute of Belgium GERB MSG RMIB GE UG Version 1 2 continued from previous page File Name Radiation Type Identifier Angles Angles Viewing Zenith Angles Relative Azimuth GERB GERB Instrument Identifier GGSPS GGSPS L1 5 NANRG File Name
17. Lop Attribute sa henee eene DO ba e a 3 26 Nr Attribute ooo ee ee RR RE ee Ak kek a 3 21 NX Attribute 2 4 2 eee a a A a ee N 9 28 Ny i Atttibute vn cae a AAD A SSS E a alee E oinicie we 4 3 29 Xp Attribute ve maniac daininga a a a a A A ER Ee a 3 30 YD Attribute 2 2 6 a a wale a a A A AAA A ea E Sol dk Attributel La a EE E E E E E E A a 3 32 dy Attribute a a a AA A ce ae e a AAA A do e A 3 33 Resolution Flags Group ee Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 34 East West Attribute 2200000 ec a 36 3 35 North South Attribute s e 36 3 36 Nominal Satellite Longitude Attribute o o e 36 3 37 Short Wave Image 1 Group e 37 3 38 Histogram of Line of Sight East West Positions Dataset 37 3 39 Short Wave Image 2 Group a A 20 ay te e aa ee a a a 37 3 40 Histogram of Line of Sight East West Positions Dataset 38 3 41 Short Wave Image 3 Group BP Sa uh A gdh re AE AOL SP EENE eB 38 3 42 Histogram of Line of Sight East West Positions Dataset 38 3 43 Total Image 1 Group rd a gh 2 Gl dal de tee hada td 39 3 44 Histogram of Line of Sight East West Positions Dataset 39 3 45 Total Image 2 Group Dr e a AE AP AE Ada a de 39 3 46 Histogram of Line of Sight East W
18. UG of Belgium GERB Version 1 2 3 77 Thermal Angular Dependency Model Dataset Description This dataset is reserved for future use It contains the identifier of the scene type dependent Angular Dependency Model that has been used to convert the emitted thermal radiance in the emitted thermal flux HDF Path Scene Identification Thermal Angular Dependency Model Additional Information Data type H5T_STD_U8BE Valid values range from 0 to 254 255 indicates an error 3 78 Solar Angular Dependency Models Set Version Attribute Description Indicates which set of solar angular dependency models has been used to determine fluxes from radiances HDF Path Scene Identification Solar Angular Dependency Models Set Version Additional Information None 3 79 Thermal Angular Dependency Models Set Version Attribute Description Indicates which set of thermal angular dependency models has been used to deter mine fluxes from radiances HDF Path Scene Identification Thermal Angular Dependency Models Set Version Additional Information None 51 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 80 Times Group Description This group gives information about the sampling time of the GERB products For the three types of products a different time sampling strategy is used and hence different time parameters are given e The high resolution product is a 15 30
19. _ lt VERSION gt hdf SHI lt GERB_ID gt _ lt IMAGER_ID gt _L20S_H_EUROPE_ lt DATE gt _ lt VERSION gt hdf SHI lt GERB_ID gt _ lt IMAGER_ID gt _L20G_H_EUROPE_ lt DATE gt _ lt VERSION gt hdf SHI lt GERB_ID gt _ lt IMAGER_ID gt _L20L_15M_50_ lt DATE gt _ lt VERSION gt hdf BARG lt GERB_ID gt _ lt IMAGER_ID gt _L20S_15M_50_ lt DATE gt _ lt VERSION gt hdf BARG lt GERB_ID gt _ lt IMAGER_ID gt _L20G_15M_50_ lt DATE gt _ lt VERSION gt hdf BARG lt GERB_ID gt _ lt IMAGER_ID gt _L20A_H_ lt DATE gt _ lt VERSION gt hdf SHI lt GERB_ID gt _ lt IMAGER_ID gt _L20G_H_ lt DATE gt _ lt VERSION gt hdf SHI 2 3 1 Table 1 L2 RMIB GERB Products lt GERB_ID gt _ lt IMAGER_ID gt _L20L_ lt DATE gt _ lt VERSION gt hdf This is an ARG product This product contains thermal fluxes and unfiltered ra diances for distribution by the GGSPS defined to be compatible with the GERB filtered radiances derived by the GGSPS Table 2 Hierarchical structure of the product L20L Access Path Name Page Summary Thermal Products Confidence 24 Duplication Flag 24 File Creation Time 25 File Name 25 Radiation Type Identifier 25 GERB 28 GERB Instrument Identifier 28 GGSPS 28 GGSPS L1 5 NANRG File Name 29 GGSPS L1 5 NANRG Product Version 29 Geolocation 29 Geolocation Geolocation File Name 32 Geolocation Line of Sight North South Speed 32 Geolocation Rectified Grid 32 Ge
20. minute snapshot at SEVIRI Meteosat7 acquistion times A time per row is given e The GERB footprint product is an average of three consecutive GERB mea surements An integration start and end time per column is given e The binned 50 km is a fixed 15 30 minute average An overall integration start and end time is given HDF Path Times Additional Information None 3 81 End of Integration Attribute Description End time of integration for the complete image HDF Path Times End of Integration Additional Information Data type H5T_C_S1 The format is YYYYMMDD HH MM ss 3 82 First GERB Packet Attribute Description In the radiance and flux files this is the acquisition time of the first GERB packet that has been used In the geolocation files the value of this field indicates the UTC time for which the data first applies HDF Path Times First GERB Packet 52 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Additional Information Data type H5T_C_S1 The format is YYYYMMDD HH MM ss 3 83 Last GERB Packet Attribute Description This is the acquisition time of the last GERB packet that has been used HDF Path Times Last GERB Packet Additional Information Data type H5T_C_S1 The format is YYYYMMDD HH MM ss 3 84 Start of Integration Attribute Description Start time of integration for the complete image
21. of Sight North South Speed 32 Geolocation Rectified Grid 32 Geolocation Rectified Grid Grid Orientation 33 Geolocation Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South 36 Geolocation Short Wave Image 1 37 Geolocation Short Wave Image 1 Histogram of Line of Sight East West Positions 37 Geolocation Short Wave Image 2 37 Geolocation Short Wave Image 2 Histogram of Line of Sight East West Positions 38 Geolocation Short Wave Image 3 38 Geolocation Short Wave Image 3 Histogram of Line of Sight East West Positions 38 Geolocation Total Image 1 39 Geolocation Total Image 1 Histogram of Line of Sight East West Positions 39 Geolocation Total Image 2 39 Geolocation Total Image 2 Histogram of Line of Sight East West Positions 40 Geolocation Total Image 3 40 Geolocation Total Image 3 Histogram of Line of Sight East West Positions 40 Geolocation Nominal Satellite Longitude 36 Imager 41 Imager Instrument Identifier 41 Imager Type 41 RMIB 41 RMIB Software Identifier 42 RMIB Product Version 42 Radiometry 42 Radiom
22. to Character String Dataset The character string dataset are not completely handle by the Lite API This paragraph introduce briefly some concepts to understand how to retrieve these datasets The information of a character string dataset can be retrieve using the same functions as for datasets H5LTget_dataset_ndims and H5LTget_dataset_info see 4 5 2 The size of one data is the number of characters including the terminating 0 of each string of the dataset A dataset is just like a string array in C the strings have the same length and are null terminated To retrieve a character string dataset the size of each string must be given as argument This is done trough the definition of a type This type should belong to the class of null terminated strings which is H5T_C_S1 and have the adequate size This is done through the follwing functions hid_t H5Tcopy hid_t type_id where type_id is the datatype to copy H5T_C_S1 for null terminated strings A negative return value indicates failure herr_t H5Tset_size hid_t type_id size_t size 3 where type_id is the identifier of datatype to change size size size in bytes to modify datatype A negative return value indicates failure The datatype identifier returned should be released with H5Tclose or resource leaks will occur herr_t H5Tclose hid_t type_id where type_id is the identifier of datatype to release A negative return value indicates failure 4 5 5 Example
23. 12 128 144 160 17 34 51 68 85 102 119 136 153 170 18 36 54 72 90 108 126 144 162 180 19 38 57 76 95 114 133 152 171 190 20 40 60 80 100 120 140 160 180 200 oono AUN ATTRIBUTE Some Attribute DATATYPE H5T_IEEE_F64BE DATASPACE SCALAR DATA 3 14159 ATTRIBUTE Some Other Attribute DATATYPE H5T_STRING 4 STRSIZE 43 STRPAD H5T_STR_NULLTERM CSET H5T_CSET_ASCIT CTYPE H5T_C_S1 DATASPACE SCALAR DATA This string is the value of the attribute Figure 6 Output of command h5dump demo hdf 65 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 A Sample Code Before being able to use the scientific data produced at RMIB the user must re trieve them from their HDF file and format them according to his needs This appendix presents sample code to help the user of the L2 RMIB GERB Products develop his own reading applications Each example is self contained except for the HDF5 Library which must be separately installed and its compilation produces an executable program Each code snippet is meant to illustrate a simple way to access a given HDF data structure and retrieve its data It should be fairly straightforward for the user to adapt the examples to his own purposes Note The programs produced out of these source codes must be given a single command line argument which is the name of an L2 RMIB GERB Product HDF fil
24. 3 2 3 8 lt GERB_ID gt _ lt IMAGER_ID gt _L20S_15M_50_ lt DATE gt _ lt VERSION gt hdf This is a BARG product comparison with model output Table 9 Hierarchical structure of the product L20S_15M_50 17 This product contains solar fluxes defined for easy Royal Meteorological Institute of Belgium MSG RMIB GE UG Version 1 2 GERB Access Path Name Page Summary Solar Products Confidence 24 Duplication Flag 24 File Creation Time 25 File Name 25 Radiation Type Identifier 25 Angles 25 Angles Viewing Zenith 27 Angles Solar Zenith 27 Angles Relative Azimuth 26 Angles Viewing Azimuth 27 GERB 28 GERB Instrument Identifier 28 GGSPS 28 GGSPS L1 5 NANRG File Name 29 GGSPS L1 5 NANRG Product Version 29 Geolocation 29 Geolocation Geolocation File Name 32 Geolocation Line of Sight North South Speed 32 Geolocation Rectified Grid 32 Geolocation Rectified Grid Grid Orientation 33 Geolocation Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South 36 Geolocation Nominal Sa
25. 36 Geolocation Nominal Satellite Longitude 36 PSF Parameters 45 Imager 41 Imager Instrument Identifier 41 Imager Type 41 RMIB 41 RMIB Software Identifier 42 RMIB Product Version 42 Radiometry 42 Radiometry Resolution Enhancement Parameters 45 Radiometry Shortwave Correction 44 Radiometry Solar Flux 45 Radiometry Solar Radiance 46 Radiometry Spectral Regression Parameters 46 Radiometry A Values per GERB detector cell 47 Radiometry C Values per GERB detector cell 48 Scene Identification 48 Scene Identification Cloud Amount 49 continued on next page 15 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 continued from previous page Scene Identification Cloud Cover 49 Scene Identification Cloud Phase 49 Scene Identification Solar Angular Dependency Model 50 Scene Identification Surface Type 50 Scene Identification Solar Angular Dependency Models Set Version 51 Times 52 Times Time per row 54 2 3 6 lt GERB_ID gt _ lt IMAGER_ID gt _L20G_H_EUROPE_ lt DATE gt _ lt VERSION gt hdf This product contains the geolocation latitude longitude for the pixels of the L20L_H_EUROPE and L20S_H_EUROPE products Table 7 Hierarchical structure of the product L20G_H_EUROPE Access Path Name Page File Creation Time 25 File Name 25 GERB 28 GERB Instrument Identifier 28 Geolocation 29 Geolocation
26. B GERB flux products are stored using a file format designed by the National Center for Super Computing Applications NCSA the Hierarchical Data Format version 5 HDF5 This document describes how to retrieve the L2 RMIB GERB scientific data from the perspective of a user who wants to use these data in his own programming applications We assume that the user s programs will be written in the C or C programming language Access to files in HDF5 format is through an application programming interface API written in C This API is provided by the HDF library A simplified version called API Lite is also available This interface is sufficient to retrieve data from RMIB hdf files 4 2 How to Obtain the L2 RMIB GERB Products A user who wishes to have access to the L2 RMIB GERB Products must register at the RMIB GERB web site http gerb oma be After the registration has been accepted the user will be able to log on to the RMIB GERB ftp site ftp gerb oma be where the HDF files of the L2 RMIB GERB Products are stored 4 3 How to Obtain the HDF5 Library Pre compiled binaries of the HDF5 libraries for various platforms are available for download at the following URL ftp ftp ncsa uiuc edu HDF HDF5 current bin This guide is certainly not a complete HDF5 reference guide For more advanced use of the HDF5 Library please refer to the full documentation set also available from the same site http hdf ncsa uiuc edu or
27. HDF Tools Provided by NCSA Several utility programs are bundled with the HDF5 library Among them h51s and h5dump are particularly useful for examining the contents of an HDF5 file The transcript in figures 5 and 6 shows the output of these two programs on the HDF file demo hdf provided with this document 63 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 dynamic version Size of dimension O is 20 Size of dimension 1 is 10 1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20 3 6 9 12 15 18 21 24 27 30 4 8 12 16 20 24 28 32 36 40 5 10 15 20 25 30 35 40 45 50 6 12 18 24 30 36 42 48 54 60 7 14 21 28 35 42 49 56 63 70 8 16 24 32 40 48 56 64 72 80 9 18 27 36 45 54 63 72 81 90 10 20 30 40 50 60 70 80 90 100 11 22 33 44 55 66 77 88 99 110 12 24 36 48 60 72 84 96 108 120 13 26 39 52 65 78 91 104 117 130 14 28 42 56 70 84 98 112 126 140 15 30 45 60 75 90 105 120 135 150 16 32 48 64 80 96 112 128 144 160 17 34 51 68 85 102 119 136 153 170 18 36 54 72 90 108 126 144 162 180 19 38 57 76 95 114 133 152 171 190 20 40 60 80 100 120 140 160 180 200 3 1415926535897931 This string is the value of the attribute static version 1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20 3 6 9 12 15 18 21 24 27 30 4 8 12 16 20 24 28 32 36 40 5 10 15 20 25 30 35 40 45 50 6 12 18 24 30 36 42 48 54 60 7 14 21 28 35 42 49 56 63 70 8 16 24 32 40 48 56 64 72 80 9 18 27 36 45 54 63 72 81 90 10 20 30 40 50
28. IB GE UG of Belgium GERB Version 1 2 3 4 File Creation Time Attribute Description The UTC time when the file was created HDF Path File Creation Time Additional Information Data type H5T_C_S1 3 5 File Name Attribute Description The name of the file HDF Path File Name Additional Information Data type H5T_C_S1 3 6 Radiation Type Identifier Attribute Description This identifier indicates on of the two possible radiation types emitted thermal radiation or reflected solar radiation HDF Path Radiation Type Identifier Additional Information Data type H5T_C_S1 Allowed values SOL for solar T H for thermal 3 7 Angles Group Description This group contains the angles that describe the viewing and solar geometry for each GERB observation 25 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 HDF Path Angles Additional Information The possible viewing and solar angles are illustrated in figure 1 Zenith A Sun Satellite Principal plane Zenith north plane Figure 1 Sun target satellite geometry Principal plane plane which contains the sun and the zenith direction Zenith north plane plane which contains the local northern direction and the zenith direction 6 solar zenith angle 0 viewing zenith angle fre relative azimuth angle yiew viewing azimuth angle 3 8 Relative A
29. L2 RMIB GERB Products User Guide Steven Dewitte Gilles Sadowski Luis Gonzalez November 25 2002 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Contents 1 Purpose of this Document 2 L2 RMIB GERB Products Files ZA AMETOAUCHON t e eld oo eb GD a de de de aod a e 22 Name Convention 0 0 0 0000 eee a 23 Products Files eve r eita Alea ee A A be ee ee eS 2 3 1 lt GERB_ID gt _ lt IMAGER ID gt _L20L_ lt DATE gt _ lt VERSION gt hdf 2 3 2 lt GERB_ID gt _ lt IMAGER_ID gt _L20S_ lt DATE gt _ lt VERSION gt hdf 2 3 3 lt GERB_ID gt _ lt IMAGER_ID gt _L20G_ lt DATE gt _ lt VERSION gt hdf 2 3 4 lt GERB_ID gt _ lt IMAGER_ID gt _L20L_H_EUROPE_ lt DATE gt _ lt VERSION gt hdf 2 3 5 lt GERB_ID gt _ lt IMAGER_ID gt _L20S_H_EUROPE_ lt DATE gt _ lt VERSION gt hdf 2 3 6 lt GERB_ID gt _ lt IMAGER_ID gt _L20G_H_EUROPE_ lt DATE gt _ lt VERSION gt hdf 2 3 7 lt GERB_ID gt _ lt IMAGER_ID gt _L20L_15M_50_ lt DATE gt _ lt VERSION gt hdf 2 3 8 lt GERB_ID gt _ lt IMAGER_ID gt _L20S_15M_50_ lt DATE gt _ lt VERSION gt hdf 2 3 9 lt GERB_ID gt _ lt IMAGER_ID gt _L20G_15M_50_ lt DATE gt _ lt VERSION gt hdf 2 3 10 lt GERB_ID gt _ lt IMAGER_ID gt _L20A_H_ lt DATE gt _ lt VERSION gt hdf 2 3 11 lt GERB_ID gt _ lt IMAGER_ID gt _L20G_H_ lt DATE gt _ lt VERSION gt hdf L2 RMIB GERB Products Contents
30. LTread_dataset file_id Times Start of Integration per column atype buffer 70 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 assert error lt 0 printf Start of Integration UTC Time n for i 0 i lt dim i printf d t s n int i buffer i type_size Release memory free buffer H5Tclose atype return 0 71 Index Angles 25 Angular Dependency Model Solar 48 Thermal 48 Angular Dependency Models Set Ver sion Solar 49 Thermal 49 Cloud Amount 47 Cover 47 Phase 47 Duplication Flag 24 dx 35 dy 35 East West Positions Histogram of Line of Sight 37 End of Integration 50 51 File Creation Time 24 Name 25 First GERB Packet 50 Flux Solar 43 Thermal 45 Geolocation 29 File Name 31 GERB 28 GGSPS 28 Grid Orientation 32 Grid Resolution East West 36 North South 36 Histogram of Line of Sight East West Positions 37 40 Imager 40 Instrument Identifier 28 41 L1 5 NANRG 72 File Name 28 Product Version 29 Lap 33 Last GERB Packet 50 Latitude 31 Line of Sight North South Speed 32 Longitude 31 Longwave Correction 42 Lop 33 main 59 64 66 68 North South Speed Line of Sight 32 Nr 33 Nx 34 Ny 34 PSF Parameters 42 Radiance Solar 44 Thermal 45 Radiation Type Identifier 25 Radiometry 42 Rectified Grid 32 Relative Azimuth 26 Resolution En
31. My Dataset dims amp class_id amp type_size assert error lt 0 Check that the dataset is of type integer 4 bytes assert class_id H5T_INTEGER assert type_size sizeof int Compute number of data points stored in the dataset num_points dims 0 dims 1 Allocate enough memory to contain all the data in the dataset data int malloc num_points sizeof int Read the data from the dataset error H5LTread_dataset_int f_id First Group My Dataset data assert error lt 0 Reading Dataset static allocation error H5LTread_dataset_int id First Group My Dataset amp data_stat 0 0 assert error lt 0 Reading Attribute Some Attribute Le Read contents of the attribute Some Attribute error H5LTget_attribute_double f_id First Group My Dataset Some Attribute amp attr_double assert error lt 0 Reading Attribute Some Other Attribute dynamic allocation qa K Check that it is a string and obtain the number of characters in the attribute value error H5LTget_attribute_info f id First Group My Dataset Some Other Attribute NULL amp type class amp attr string siz assert error lt 0 amp amp type_class H5T_STRING Allocate enough memory to contain the string attr_string_dyn char malloc attr_string_size
32. NRG Product Version 29 Geolocation 29 Geolocation Latitude 30 Geolocation Longitude 31 Geolocation Geolocation File Name 32 Geolocation Line of Sight North South Speed 32 Geolocation Rectified Grid 32 Geolocation Rectified Grid Grid Orientation 33 Geolocation Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South 36 Geolocation Short Wave Image 1 37 Geolocation Short Wave Image 1 Histogram of Line of Sight East West Positions 37 Geolocation Short Wave Image 2 37 Geolocation Short Wave Image 2 Histogram of Line of Sight East West Positions 38 Geolocation Short Wave Image 3 38 Geolocation Short Wave Image 3 Histogram of Line of Sight East West Positions 38 Geolocation Total Image 1 39 Geolocation Total Image 1 Histogram of Line of Sight East West Positions 39 Geolocation Total Image 2 39 Geolocation Total Image 2 Histogram of Line of Sight East West Positions 40 Geolocation Total Image 3 40 Geolocation Total Image 3 Histogram of Line of Sight East West Positions 40 Geolocation Nominal Satellite Longitude 36 Imag
33. RG Product Version 29 Geolocation 29 Geolocation Geolocation File Name 32 Geolocation Line of Sight North South Speed 32 Geolocation Rectified Grid 32 Geolocation Rectified Grid Grid Orientation 33 Geolocation Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South 36 Geolocation Nominal Satellite Longitude 36 PSF Parameters 45 Imager 41 Imager Instrument Identifier 41 Imager Type 41 RMIB 41 RMIB Software Identifier 42 RMIB Product Version 42 Radiometry 42 Radiometry Longwave Correction 43 Radiometry Resolution Enhancement Parameters 45 Radiometry Spectral Regression Parameters 46 Radiometry Thermal Flux 4T Radiometry Thermal Radiance AT Radiometry A Values per GERB detector cell 47 Radiometry C Values per GERB detector cell 48 Scene Identification 48 Scene Identification Thermal Angular Dependency Model 5l Scene Identification Thermal Angular Dependency Models Set Version 51 Times 52 Times Time per row 54 2 3 5 lt GERB_ID gt _ lt IMAGER_ID gt _L20S_H_EUROPE_ lt DATE gt _ lt VERSION
34. a geostationary satellite viewing the earth in an equi angular projection are illustrated in figure 2 The earth reference ellipsoid is defined by a polar radius Rp and an equatorial radius Rp D 42144km Earth Ellipsoid E grid cell of equi angular grid Figure 2 Geolocation parameters Left intersection of the lines of sight of a geostationary satellite with the earth reference ellipsiod Right the corresponding equi angular grid projection of the earth as viewed from the satellite Consider the right hand axis system where the origin is the centre of the earth the XY plane is the equatorial plane the YZ plane is the Greenwhich meridian plane and the Z axis points northwards see figure 3 A point P on the earth reference ellipsoid with longitude and geocentric latitude 0 has the cartesian coordinates X Rpg cos cos 0 Y Resin cos 0 1 Z Rpsin 0 The geodetic vertical in the point P is defined as the outer normal to the earth refer ence ellipsoid in P The geodetic latitude of the point P is the angle from the equato rial plane towards the geodetic vertical in P The relationship between the geocentric latitude 0 and the geodetic latitude 04 is given by tan 6z Rg Rp tan 0 3 18 Latitude Dataset Description See figures 2 and 3 The geodetic latitude is given for every GERB observation point The GERB observation point is the intersection of the GERB line of sight and the e
35. adiances and GERB filtered radiances from the imager data HDF Path Radiometry Spectral Regression Parameters Additional Information Data type H5T_IEEE_F64BE 46 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 67 Thermal Flux Dataset Description This dataset contains the surface density of the radiative flux of emitted thermal energy at the top of the atmosphere referenced at the earth reference ellipsoid surface HDF Path Radiometry Thermal Flux Additional Information The earth surface can be calculated at different heights above the earth reference ellipsoid Because the surface increases with height above the reference ellipsoid the flux surface density decreases with height by a factor R R hy with R the local radius of the reference ellipsoid and h the height above the reference ellipsoid Quantisation factor 0 25 W m Data type H5T_STD_I16BE Error value 32767 Range 150 450 W m 3 68 Thermal Radiance Dataset Description This dataset contains the GERB measured radiance of emitted energy at the top of the atmosphere HDF Path Radiometry Thermal Radiance Additional Information Quantisation factor 0 05 W m sr Data type H5T_STD_I16BE Error value 32767 Range 50 150 W m 3 69 A Values per GERB detector cell Dataset Description The A value is used for the definition of the GERB synthetic longwave filt
36. arth reference ellipsoid The geodetic latitude of the point P is the angle from the equatorial plane towards the geodetic vertical in P The geodetic vertical in the point P is defined as the outer normal to the earth reference ellipsoid in P HDF Path Geolocation Latitude 30 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Z North geocentric vertical X Figure 3 Geodetic versus geocentric geolocation 0e geocentric latitude 0q geodetic latitude geodetic or geocentric longitude Additional Information Quantisation factor Ds degree Data type H5T_STD_I16BE Error value 32767 Range 90 90 degree 3 19 Longitude Dataset Description See figures 2 and 3 The longitude is given for every GERB observation point The GERB observation point is the intersection of the GERB line of sight and the earth reference ellipsoid The longitude of the point P is the angle from the Greenwhich meridian plane towards P positive in eastward direction HDF Path Geolocation Longitude Additional Information ES ing degree Quantisation factor 31 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Data type H5T_STD_I16BE Error value 32767 Range 180 180 degree 3 20 Geolocation File Name Attribute Description Name of the geolocation file which contains the latitude and longitude for each pixel HDF Path
37. ationary Earth Radiation Budget GERB instrument data These L2 prod ucts are computed at the Royal Meteorological Institute of Belgium RMIB The L2 RMIB GERB Products consist of images of unfiltered radiances and radiative fluxes at the top of the atmosphere together with some auxiliary information Un filtered radiances and radiative fluxes are available for reflected solar radiation and for emitted thermal radiation The data format chosen for the L2 RMIB GERB Products is the Hierarchical Data Format HDF version 5 HDF is not a straightforward data file format in which data items are accessed from byte location Instead data items in an HDF file format are accessed by name using HDF library functions Documents detailing the scientific assumptions and algorithms used to derive the L2 RMIB GERB Products are available from our web site http gerb oma be Any suggestion information or correction can be sent to gerbQoma be This document is organised as follows e Section 2 gives an overview of each of the various L2 RMIB GERB Products e Section 3 provides a detailed description of the logical contents of the products e Section 4 describes how a user can write an application to read the L2 RMIB GERB Products e Appendix A contains sample code that can help the user devise his own reading programs for the L2 RMIB GERB Products Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 2 L2 RMIB GERB Produc
38. calibration documentation 3 71 Scene Identification Group Description This group contains auxiliary scene identification given with the GERB measure ments Scene identification is only given during daytime The given scene iden tification is the most accurate for the high resolution and for the binned 50 km resolution products It is only indicative for the GERB footprint product HDF Path Scene Identification 48 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Additional Information None 3 72 Cloud Amount Dataset Description The cloud amount is defined as L L 5 Linick Les where L is the measured 0 6 micron SEVIRI radiance Les is the corresponding clear sky radiance and Lov is the theoretical radiance for an optically thick cloud A cloud amount of 1 corresponds to an infinitely thick cloud a cloud amount of 0 corresponds to an infinitely thin cloud HDF Path Scene Identification Cloud Amount Additional Information Data type H5T_STD_U8BE 255 indicates an error 3 73 Cloud Cover Dataset Description The cloud cover is the relative number of cloudy imager pixels in the GERB footprint or grid cell A cloud cover of 0 corresponds to a clear sky footprint A cloud cover of 100 corresponds to an overcast footprint HDF Path Scene Identification Cloud Cover Additional Information Data type H5T_STD_U8BE Error Value 255 Range 1 100
39. ccess Path Name Page File Creation Time 25 File Name 25 GERB 28 GERB Instrument Identifier 28 Geolocation 29 Geolocation Latitude 30 Geolocation Longitude 31 Geolocation Rectified Grid 32 Geolocation Rectified Grid Grid Orientation 33 Geolocation Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South 36 RMIB 41 RMIB Software Identifier 42 continued on next page 21 pixels of the MSG RMIB GE UG Royal Meteorological Institute GERB Version 1 2 of Belgium continued from previous page RMIB Product Version 42 Times 52 Times First GERB Packet 52 22 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 L2 RMIB GERB Products Contents This section describes the contents of the fields from which the L2 products are composed For each HDF field the following information is provided e The field name e The HDF object type see 4 4 1 is indicated between square brackets e A description of the field contents e The absolute name see 4 4 2 of the
40. ce date is used to identify the successive files The format of this reference date is lt DATE gt i e four digit year two digit month two digit day an underscore character two digit hour two digit minute and two digit second The last part specifies the product version The first value is V001 Finally the HDF file format is indicated by the extension hdf gz with optional gzip compression 2 3 Products Files Table 1 lists the name and product type of all eleven L2 RMIB GERB Products files see section 2 2 about the file naming convention Each of the following sections is devoted to one specific L2 RMIB GERB product The section title indicate the product file name as described in 2 2 For each product a table presents the logical structure of the data it contains The first column of the table gives the name of the data see section 4 on how to use that name to access the data the number in the second column is the page of this document where the user can find a complete description of the data Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 File Name Type lt GERB_ID gt _ lt IMAGER_1D gt _L20L_ lt DATE gt _ lt VERSION gt hdf ARG lt GERB_ID gt _ lt IMAGER_ID gt _L20S_ lt DATE gt _ lt VERSION gt hdf ARG lt GERB_ID gt _ lt IMAGER_ID gt _L20G_ lt DATE gt _ lt VERSION gt hdf ARG lt GERB_ID gt _ lt IMAGER_ID gt _L20L_H_EUROPE_ lt DATE gt
41. df5 h gt ttinclude lt H5LT h gt The assert macro is used to detect any error and exit from the program in case something went wrong include lt assert h gt define XDIM 256 define YDIM 256 herr_t H5LTread_dataset_uchar hid_t loc_id const char dset_name char data int main int argc char argv char file_name 67 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 hid_t file_id herr_t error int i j unsigned char surface_type YDIM XDIM The argument on the command line is the name of an HDF file which must contain a Scene Identification Surface Type dataset of size 256 x 256 The dataset values are integers Each value is an index representing a surface type O undefined 1 ocean 2 dark vegetation 3 bright vegetation 4 dark desert 5 bright desert 6 snow 255 error assert argc 2 filename argv 1 Open the HDF file file_id H5Fopen filename H5F_ACC_RDONLY H5P_DEFAULT assert file_id gt 0 Obtain the data stored in the Scene Identification Surface Type dataset error H5LTread_dataset_uchar file_id Scene Identification Surface Type surface_type 0 assert error lt 0 Print the surface type indices to standard output for i 0 i lt YDIM i for j 0 j lt XDM j printf d surface_typeli j printf Na return 0
42. e This file must obviously contain the HDF structure that the program wants to read see comments embedded in the code or an error will occur A 1 Float Image The following code illustrates how to extract a float image from quantised data stored in a 2 dimensional dataset The quantisation factor is stored as a dataset attribute of type double This is the factor by which each element from the dataset must be multiplied to obtain a meaningful value In the example below this means that to obtain the physical value of the solar flux in watts per square meter one must multiply the dataset data count value by the value of the quantisation factor The source code file name is read_rgp_float_dataset c include lt stdio h gt include lt stdlib h gt HDF5 Library header file include lt hdf5 h gt include lt H5LT h gt The assert macro is used to detect any error and exit from the program in case something went wrong include lt assert h gt define XDIM 256 define YDIM 256 int main int argc char argv char file_name hid_t file_id herr_t error int i j int solar_flux_int16 YDIM XDIM float solar_flux YDIM XDIM double quantisation_factor The argument on the command line is the name of an HDF file The file must contain a Radiometry Solar Flux dataset of size 256 x 256 The dataset values are integers Each value results from the quantisation of float va
43. e angle from the zenith direction towards the target solar direction The target is the observed scene on the surface of the earth characterised by its geodetic geolocation parameters The zenith direction is the local geodetic vertical direction HDF Path Angles Solar Zenith Additional Information Quantisation factor 1 degree Data type H5T_STD_I8BE Error value 255 Range 0 180 degree 3 11 Viewing Zenith Dataset Description See figure 1 The viewing zenith angle 0 is the angle from the zenith direction towards the target satellite direction The target is the observed scene on the sur face of the earth characterised by its geodetic geolocation parameters The zenith direction is the local geodetic vertical direction 27 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 HDF Path Angles Viewing Zenith Additional Information Quantisation factor 1 degree Data type H5T_STD_I8BE Error value 255 Range 0 90 degree 3 12 GERB Group Description This group contains information regarding the GERB instrument that was used HDF Path GERB Additional Information None 3 13 Instrument Identifier Attribute Description This identifier indicates which GERB instrument is used HDF Path GERB Instrument Identifier Additional Information Data type H5T_C_S1 Allowed values GERB1 GERB2 GERB3 3 14 GGSPS Group
44. ed Non Rectified Geolo cated NANRG GERB radiance product that has been used as input file This dataset contains the histogram of the measured east west deviations of the GERB line of sight from its nominal position One histogram is given for every image column of the second GERB short wave image HDF Path Geolocation Short Wave Image 2 Histogram of Line of Sight East West Positions Additional Information Data type H5T_STD_U8BE 3 41 Short Wave Image 3 Group Description This group contains geolocation information for the third of the three GERB short wave images that have been used as input HDF Path Geolocation Short Wave Image 3 Additional Information None 3 42 Histogram of Line of Sight East West Positions Dataset Description This information is copied from the level 1 5 Non Averaged Non Rectified Geolo cated NANRG GERB radiance product that has been used as input file This dataset contains the histogram of the measured east west deviations of the GERB line of sight from its nominal position One histogram is given for every image column of the third GERB short wave image HDF Path Geolocation Short Wave Image 3 Histogram of Line of Sight East West Positions 38 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Additional Information Data type H5T_STD_U8BE 3 43 Total Image 1 Group Description This group contains geolocation information for t
45. er 41 Imager Instrument Identifier 41 Imager Type 41 RMIB 41 RMIB Software Identifier 42 RMIB Product Version 42 Radiometry 42 continued on next page 20 Royal Meteorological Institute of Belgium GERB MSG RMIB GE UG Version 1 2 continued from previous page Radiometry Longwave Correction Radiometry Resolution Enhancement Parameters Radiometry Shortwave Correction Radiometry Solar Flux Radiometry Solar Radiance Radiometry Spectral Regression Parameters Radiometry Thermal Flux Radiometry Thermal Radiance Radiometry A Values per GERB detector cell Radiometry C Values per GERB detector cell Scene Identification Scene Identification Cloud Amount Scene Identification Cloud Cover Scene Identification Cloud Phase Scene Identification Solar Angular Dependency Model Scene Identification Surface Type Scene Identification Thermal Angular Dependency Model Scene Identification Solar Angular Dependency Models Set Version Scene Identification Thermal Angular Dependency Models Set Version Times Times Time per row 43 45 44 45 46 46 47 47 47 48 48 49 49 49 50 50 5l 5l 5l 52 54 2 3 11 lt GERB ID gt _ lt IMAGER ID gt _L20G_H_ lt DATE gt _ lt VERSION gt hdf This product contains the geolocation latitude longitude for the L20A_H product Table 12 Hierarchical structure of the product L20G_H A
46. ered radiance A is defined as the ratio between the GERB filtered total radiance and the GERB filtered short wave radiance for a 5800 K black body The given A values are copied from the level 1 5 Non Averaged Non Rectified Geolocated NANRG 47 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 GERB radiance product that has been used as input file They are measured with the sunlit onboard solar diffuser sphere There are one value for each detector If more than one NANRG file has been used the used A values are the ones of the main file TBC HDF Path Radiometry A Values per GERB detector cell Additional Information Data type H5T_IEEE_64BE See GERB calibration documentation 3 70 C Values per GERB detector cell Dataset Description The C value is used to monitor the longwave leakage of the GERB quartz filter C is defined as the ratio between the GERB filtered shortwave radiance and the GERB filtered total radiance for a 300 K black body The given C values are copied from the level 1 5 Non Averaged Non Rectified Geolocated NANRG GERB radiance product that has been used as input file They are measured with the onboard black body If more than one NANRG file has been used the used A values are the ones of the main file TBC HDF Path Radiometry C Values per GERB detector cell Additional Information Data type H5T_IEEE_64BE See GERB
47. escription Longitude of sub satellite point HDF Path Geolocation Rectified Grid Lop Additional Information Units Degree Data type H5T_IEEE_F64BE 3 26 Nr Attribute Description The altitude of the imaging device from the earth s center measured in units of the earth s equatorial radius 33 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 HDF Path Geolocation Rectified Grid Nr Additional Information Units Earth radius Data type H5T_IEEE_F64BE 3 27 Nx Attribute Description Number of points along x axis number of columns width image HDF Path Geolocation Rectified Grid Nx Additional Information Data type H5T_STD_I32BE 3 28 Ny Attribute Description Number of points along y axis number of rows height image HDF Path Geolocation Rectified Grid Ny Additional Information Data type H5T_STD_I32BE 3 29 Xp Attribute Description X coordinate of sub satellite point HDF Path Geolocation Rectified Grid Xp Additional Information Units Grid length Data type H5T_IEEE_F64BE 34 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 30 Yp Attribute Description Y coordinate of sub satellite point HDF Path Geolocation Rectified Grid Yp Additional Information Units Grid length Data type H5T_IEEE_F64BE 3 31 dx Attribute Description Appa
48. est Positions Dataset 40 3 47 Total Image 3 Group sheep ch ti el oe 40 3 48 Histogram of Line of Sight East West Positions Dataset 40 3 49 Imager Group ida ada AA ta EE a a 41 3 50 Instrument Identifier Attribute a 41 S51 Type Attributel is jo a ala ae A A ee Le e 41 3 52 RMIB Group ict aara dd dd ca A na 41 3 53 Software Identifier Attribute o o e e e 42 3 54 Product Version Attribute ee 42 3 09 Radiometry Group si BARA ee e dd Gee 42 3 56 Longwave Correction Dataset o o e 43 3 57 Longwave Minimum Correction Value Attribute o 43 3 58 Longwave Maximum Correction Value Attribute o 43 3 59 Shortwave Correction Dataset 2 0 0 e ee eee 44 3 60 Shortwave Minimum Correction Value Attribute o o 44 3 61 Shortwave Maximum Correction Value Attribute 44 3 62 PSF Parameters Group 45 3 63 Resolution Enhancement Parameters Dataset o o 45 3 04 Solar Flux Dataset ina s retina e e ede at ee A 45 3 65 Solar Radiance Dataset a 46 3 66 Spectral Regression Parameters Dataset o o e 46 3 67 Thermal Flux Dataset e ee ee 47 3 68 Thermal Radiance Dataset o e 47 3
49. et_ndims and H5LTget_dataset_info The first returns the dimensionality of a dataset herr_t H5LTget_dataset_ndims hid_t loc_id const char dset_name int rank where loc_id is the file ID dset_name is the datset name rank is filled with the dimensionality of the dataset A negative return value indicates failure The second returns the size of each dimension the data class and the data size herr_t H5LTget_dataset_info hid_t loc_id const char dset_name hsize_t dims H5T_class_t class_id size_t type_size where loc_id is the file ID dset_name is the dataset name dims is filled with the size of each dimension class_id is filled with the data class identifier type_size is filled with the size of the datatype in bytes A negative return value indi cates failure dims must point to previously allocated memory of sufficient size sizeof size_t rank where rank has been determined by a call to H5LTget_dataset_ndims 4 5 3 Attribute Access An attribute is primarily used to provide single valued metadata information to another HDF5 object group or dataset The value of the attribute is retrieved by a call to the function H5LTget_attribute_ typel 0 herr_t H5LTget_attribute_ typel hid_t loc_id const char obj_name const char attr_name type data Jas 58 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 where type can take one of the following values string char sho
50. etry Shortwave Correction 44 Radiometry Shortwave Correction Minimum Correction Value 44 Radiometry Shortwave Correction Maximum Correction Value 44 Radiometry Solar Flux 45 Radiometry Solar Radiance 46 Radiometry Spectral Regression Parameters 46 Radiometry A Values per GERB detector cell AT Radiometry C Values per GERB detector cell 48 Scene Identification 48 Scene Identification Cloud Amount 49 Scene Identification Cloud Cover 49 Scene Identification Cloud Phase 49 Scene Identification Surface Type 50 Scene Identification Solar Angular Dependency Models Set Version 51 Times 52 continued on next page 12 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 continued from previous page Times First GERB Packet 52 Times Last GERB Packet 53 Times End of Integration per column 53 Times Start of Integration per column 54 2 3 3 lt GERB_ID gt _ lt IMAGER_ID gt _L20G_ lt DATE gt _ lt VERSION gt hdf This product contains the geolocation latitude longitude for the pixels of the L20L and L209 products Table 4 Hierarchical structure of the product L20G Access Path Name Page File Creation Time 25 File Name 25 GERB 28 GERB Instrument Identifier 28 Geolocation 29 Geolocation Latitude 30 Geolocation Longitude 31 Geolocation Rectified Grid 32 Geolocation Rectified Grid Grid Orientation 33 Geo
51. fied Grid 32 Geolocation Rectified Grid Grid Orientation 33 Geolocation Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South 36 RMIB 41 RMIB Software Identifier 42 RMIB Product Version 42 Times 52 Times First GERB Packet 52 This is a SHI product defined over the full MSG disc It is not intended for routine distribution lt GERB_ID gt _ lt IMAGER_ID gt _L20A_H_ lt DATE gt _ lt VERSION gt hdf Table 11 Hierarchical structure of the product L20A_H Access Path Name Page Summary Thermal Products Confidence 24 Summary Solar Products Confidence 24 Duplication Flag 24 continued on next page 19 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 continued from previous page File Creation Time 25 File Name 25 Angles 25 Angles Viewing Zenith 27 Angles Solar Zenith 27 Angles Relative Azimuth 26 Angles Viewing Azimuth 27 GERB 28 GERB Instrument Identifier 28 GGSPS 28 GGSPS L1 5 NANRG File Name 29 GGSPS L1 5 NA
52. field e If need be some additional information 23 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 1 Summary Thermal Products Confidence Attribute Description Product confidence summary value indicating overall usefulness of thermal products This is the ratio of pixels that are valid A valid pixel is one that is in the range defined by 3 60 and 3 61 HDF Path Summary Thermal Products Confidence Additional Information Data type HST_IEEE_F64BE 3 2 Summary Solar Products Confidence Attribute Description Product confidence summary value indicating overall usefulness of solar products This is the ratio of pixels that are valid A valid pixel is one that is in the range defined by 3 57 and 3 58 HDF Path Summary Solar Products Confidence Additional Information Data type HST_IEEE_F64BE 3 3 Duplication Flag Attribute Description This flag is copied from the level 1 5 Non Averaged Non Rectified Geolocated NANRG GERB radiance product that has been used as input file It indicates whether this NANRG product appears in two fifteen minute slots and if so if it is the first or second duplication HDF Path Duplication Flag Additional Information Data type H5T_STD_I32BE Allowed values 0 no duplication 1 nominal file 2 duplicated file See level 1 5 NANRG documentation for comlplete information 24 Royal Meteorological Institute MSG RM
53. fine NUMCOLUMNS 256 int main int argc char argv char file name hid_t file_id herr_t error hsize_t dim i hid_t atype int rank char buffer NULL size_t type size H5T_class_t class_id The argument on the command line is the name of an HDF file which must contain a Times Start of Integration per column group which itself contains a list of 256 string attributes The names of these attributes are the string representation in base 10 of the numbers between 0 and 255 inclusive assert argc 2 filename argv 1 Open the HDF file file_id H5Fopen filename H5F_ACC_RDONLY H5P_DEFAULT assert file_id gt 0 obtain the dimensions of the dataset error H5LTget_dataset_ndims file_id Times Start of Integration per column amp rank assert error lt 0 amp amp rank 1 obtain information about the dataset error H5LTget_dataset_info file_id Times Start of Integration per column amp dim amp class_id amp type size assert error lt 0 amp amp class_id H5T_STRING allocate the buffer buffer char malloc sizeof char dim type_size create a data type according to the dataset type strings null terminated of size type_size atype H5Tcopy H5T_C_S1 assert atype lt 0 error H5Tset_size atype type_size assert error lt 0 read the dataset error H5
54. ftp ftp ncsa uiuc edu HDF HDF5 docs 4 4 Overview of HDF5 4 4 1 Objects e File objects represent the HDF file e Dataset objects are used for storing multi dimensional arrays of data e Group objects serve as containers for other HDF5 objects e Attribute objects are used for single valued data that characterise another ob ject either a group or a dataset 55 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 4 4 2 Hierarchical Layout At the API level the layout of an HDF5 file takes the form of a hierarchical struc ture In fact the data organisation closely resembles that of the UNIX file system An object in an HDF5 file takes on the role of a file in the UNIX file system At creation time an HDF5 object must be given a name i e a string of characters The name can be either absolute i e starting with a character or relative i e not starting with a character The serves as a delimiter and indicates that the object whose name starts at the next character stands one level deeper in the HDF5 hierarchy At the top of the hierarchy stands the root group object whose name is a single slash The root group is automatically created at the file creation even if the HDF file is otherwise empty i e it does not contain any user data Each data structure within the HDF5 file is unequivocally identified by its absolute name A base name is a relative name that does
55. gt hdf This is a SHI product defined in a window over Europe This product contains solar radiances and fluxes defined to be compatible with the SEVIRI radiance images It can e g be used together with SEVIRI derived cloud products Table 6 Hierarchical structure of the product L20S_H_EUROPE 14 Royal Meteorological Institute of Belgium MSG RMIB GE UG Version 1 2 GERB Access Path Name Page Summary Solar Products Confidence 24 Duplication Flag 24 File Creation Time 25 File Name 25 Radiation Type Identifier 25 Angles 25 Angles Viewing Zenith 27 Angles Solar Zenith 27 Angles Relative Azimuth 26 Angles Viewing Azimuth 27 GERB 28 GERB Instrument Identifier 28 GGSPS 28 GGSPS L1 5 NANRG File Name 29 GGSPS L1 5 NANRG Product Version 29 Geolocation 29 Geolocation Geolocation File Name 32 Geolocation Line of Sight North South Speed 32 Geolocation Rectified Grid 32 Geolocation Rectified Grid Grid Orientation 33 Geolocation Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South
56. hancement Parameters 43 Flags 35 RMIB 41 Scene Identification 46 Short Wave Image 1 36 Image 2 37 Image 3 38 Shortwave Correction 43 Software Identifier 41 Solar Angular Dependency Model 48 Angular Dependency Models Set Version 49 Flux 43 Royal Meteorological Institute of Belgium GERB MSG RMIB GE UG Version 1 2 Radiance 44 Zenith 27 Spectral Regression Parameters 44 Start of Integration 51 Start of Integration per column 51 Summary Solar Products Confidence 24 Summary Thermal Products Confidence 24 Surface Type 48 Thermal Angular Dependency Model 48 Angular Dependency Models Set Version 49 Flux 45 Radiance 45 Time per row 51 Times 49 Total Image 1 38 Image 2 39 Image 3 40 Type 41 Values A 45 C 46 Viewing Azimuth 26 Zenith 27 Xp 34 Yp 34 73
57. he first of the three GERB total images that have been used as input HDF Path Geolocation Total Image 1 Additional Information None 3 44 Histogram of Line of Sight East West Positions Dataset Description This information is copied from the level 1 5 Non Averaged Non Rectified Geolo cated NANRG GERB radiance product that has been used as input file This dataset contains the histogram of the measured east west deviations of the GERB line of sight from its nominal position One histogram is given for every image column of the first GERB total image HDF Path Geolocation Total Image 1 Histogram of Line of Sight East West Posi tions Additional Information Data type H5T_STD_U8BE 3 45 Total Image 2 Group Description This group contains geolocation information for the second of the three GERB total images that have been used as input HDF Path Geolocation Total Image 2 Additional Information None 39 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 46 Histogram of Line of Sight East West Positions Dataset Description This information is copied from the level 1 5 Non Averaged Non Rectified Geolo cated NANRG GERB radiance product that has been used as input file This dataset contains the histogram of the measured east west deviations of the GERB line of sight from its nominal position One histogram is given for every image column of the sec
58. imit of the range is applied see 3 60 and 3 61 HDF Path Radiometry Shortwave Correction Additional Information Quantisation factor 0 005 Offset 1 Data type H5T_STD_I8BE Range 1 635 1 635 3 60 Shortwave Minimum Correction Value Attribute Description If the shortwave ratio between GERB and SEVIRI is lower than this value this value has been applied as correction HDF Path Radiometry Shortwave Correction Minimum Correction Value Additional Information Data type H5T_IEEE_F64BE If no lower limit has been used this value is 1 3 61 Shortwave Maximum Correction Value Attribute Description If the shortwave ratio between GERB and SEVIRI is higher than this value this value has been applied as correction HDF Path Radiometry Shortwave Correction Maximum Correction Value 44 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Additional Information Data type H5T_IEEE_F64BE If no upper limit has been used this value is 1 3 62 PSF Parameters Group Description This group contains information about dynamic behaviour of GERB acquisition The content is still TBD HDF Path PSF Parameters Additional Information None 3 63 Resolution Enhancement Parameters Dataset Description This dataset contains the parameters that have been used for the resolution en hancement of GERB data by imager data The imager can be the METEOSAT o
59. ize in bytes of one datasat data size_t type_size Will contain the data from First Group My Dataset int data NULL data_stat DIM_0 DIM_1 Will contain the class identifier of the dataset Outside the scope of this simple demo H5T_class_t class_id Will contain the value of attribute First Group My Dataset Some Attribute double attr_double Will contain number of characters in attribute First Group My Dataset Some Other Attribute size_t attr_string_size Will contain the value of attribute First Group My Dataset Some Other Attribute char attr_string dyn NULL attr_string_stat 256 Error reporting herr_t error Will contain the data type of attribute First Group My Dataset Some Other Attribute H5T_class_t type_class int n ij Open the file f id H5Fopen filename H5F_ACC_RDONLY H5P_DEFAULT assert f id gt 0 Reading Dataset dynamic allocation 61 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Retrieve the number of dimensions error H5LTget_dataset_ndims f_id First Group My Dataset amp num_dims assert error lt 0 assert num_dims 2 Allocate array to contain the size of each dimension dims hsize_t malloc num_dims sizeof hsize_t Retrieve the dimension sizes error H5LTget_dataset_info f_id First Group
60. location Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South 36 RMIB 41 RMIB Software Identifier 42 RMIB Product Version 42 Times 52 Times First GERB Packet 52 2 3 4 lt GERB_ID gt _ lt IMAGER_ID gt _L20L_H_EUROPE_ lt DATE gt _ lt VERSION gt hdf This is a SHI product defined in a window over Europe This product contains thermal radiances and fluxes defined to be compatible with the SEVIRI radiance images It can e g be used together with SEVIRI derived cloud products Table 5 Hierarchical structure of the product L20L_H_EUROPE Access Path Name Page Summary Thermal Products Confidence 24 File Creation Time 25 File Name 25 Radiation Type Identifier 25 Angles 25 continued on next page 13 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 continued from previous page Angles Viewing Zenith 27 Angles Relative Azimuth 26 GERB 28 GERB Instrument Identifier 28 GGSPS 28 GGSPS L1 5 NANRG File Name 29 GGSPS L1 5 NAN
61. lues representing solar fluxes in watts per meter square The quantisation factor is stored as an attribute of the dataset 66 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 assert argc 2 filename argv 1 Open the HDF file file_id H5Fopen filename H5F_ACC_RDONLY H5P_DEFAULT assert file_id lt 0 Obtain the data stored in the Radiometry Solar Flux dataset error H5LTread_dataset_int file_id Radiometry Solar Flux solar_flux_int16 0 assert error lt 0 Obtain the value of the Quantisation Factor attribute inside the dataset error H5LTget_attribute_double file_id Radiometry Solar Flux Quantisation Factor amp quantisation_factor assert error lt 0 Close the HDF file error H5Fclose file_id assert error lt 0 Compute the float values of the solar flux and print them to standard output for i 0 i lt YDIM i for j 0 j lt XDIM j solar_flux i j quantisation_factor solar_flux_int16 i j printf 2f solar_flux i j printf Na return 0 A 2 Integer Image This code also extracts an image but does not perform integer to float conversion The source code file name is read_rgp_integer_dataset c include lt stdio h gt include lt stdlib h gt HDF5 Library header file include lt h
62. not contain any character except maybe as the last character of a group name For example if e First Group is the base name of a group object e My Dataset is the base name of a dataset object located in the group above e Some Attribute is the base name of an attribute object of the preceding dataset then the absolute name of Some Attribute is First Group My Dataset Some Attribute 4 4 3 API The HDF5 library API is a set of C functions that manipulates the contents of HDF files The creation writing reading and deletion of all HDF5 objects is done through this API The functions names are composed from the concatenation of the following parts 1 The library identifier prefix H5 2 A letter specifying which type of object the function is concerned with F for a file object G for a group D for a dataset A for an attribute S for a data space object and T for a data type object 3 A string referring to type of action the function performs For example H5Dread names a function that is concerned with the reading of data stored in a dataset object The library references an HDF5 object through a unique identifier the data type of which is hid_t This identifier is supplied by an open function specific to each type of HDF5 object which is given the name of the object see 4 4 2 as one of its arguments 56 Royal Meteorological
63. olocation Rectified Grid Grid Orientation 33 Geolocation Rectified Grid Lap 33 Geolocation Rectified Grid Lop 33 Geolocation Rectified Grid Nr 33 Geolocation Rectified Grid Nx 34 Geolocation Rectified Grid Ny 34 Geolocation Rectified Grid Xp 34 Geolocation Rectified Grid Yp 35 Geolocation Rectified Grid dx 35 Geolocation Rectified Grid dy 35 Geolocation Rectified Grid Resolution Flags 35 Geolocation Rectified Grid Resolution Flags East West 36 Geolocation Rectified Grid Resolution Flags North South 36 continued on next page 10 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 continued from previous page Geolocation Short Wave Image 1 37 Geolocation Short Wave Image 1 Histogram of Line of Sight East West Positions 37 Geolocation Short Wave Image 2 37 Geolocation Short Wave Image 2 Histogram of Line of Sight East West Positions 38 Geolocation Short Wave Image 3 38 Geolocation Short Wave Image 3 Histogram of Line of Sight East West Positions 38 Geolocation Total Image 1 39 Geolocation Total Image 1 Histogram of Line of Sight East West Positions 39 Geolocation Total Image 2 39 Geolocation Total Image 2 Histogram of Line of Sight East West Positions 40 Geolocation Total Image 3 40 Geolocation Total Image 3 Histogram of Line of Sight East West Positions 40 Geolocation Nominal Satellite Longitude 36 Imager 41 Imager Instrument Identifier 41 Imager Type
64. onal Information Units Degree Data type H5T_IEEE_F64BE 36 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 37 Short Wave Image 1 Group Description This group contains geolocation information for the first of the three GERB short wave images that have been used as input HDF Path Geolocation Short Wave Image 1 Additional Information None 3 38 Histogram of Line of Sight East West Positions Dataset Description This information is copied from the level 1 5 Non Averaged Non Rectified Geolo cated NANRG GERB radiance product that has been used as input file This dataset contains the histogram of the measured east west deviations of the GERB line of sight from its nominal position One histogram is given for every image column of the first GERB short wave image HDF Path Geolocation Short Wave Image 1 Histogram of Line of Sight East West Positions Additional Information Data type H5T_STD_U8BE 3 39 Short Wave Image 2 Group Description This group contains geolocation information for the second of the three GERB short wave images that have been used as input HDF Path Geolocation Short Wave Image 2 Additional Information None 37 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 40 Histogram of Line of Sight East West Positions Dataset Description This information is copied from the level 1 5 Non Averag
65. ond GERB total image HDF Path Geolocation Total Image 2 Histogram of Line of Sight East West Posi tions Additional Information Data type H5T_STD_U8BE 3 47 Total Image 3 Group Description This group contains geolocation information for the third of the three GERB total images that have been used as input HDF Path Geolocation Total Image 3 Additional Information None 3 48 Histogram of Line of Sight East West Positions Dataset Description This information is copied from the level 1 5 Non Averaged Non Rectified Geolo cated NANRG GERB radiance product that has been used as input file This dataset contains the histogram of the measured east west deviations of the GERB line of sight from its nominal position One histogram is given for every image column of the third GERB total image HDF Path Geolocation Total Image 3 Histogram of Line of Sight East West Posi tions 40 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Additional Information Data type H5T_STD_U8BE 3 49 Imager Group Description This group contains information about the imager SEVIRI or METEOSAT that has been used as auxiliary data in the processing of GERB data HDF Path Imager Additional Information None 3 50 Instrument Identifier Attribute Description This identifier indicates which imager of a particular type has been used HDF Path Image
66. or read only access access_properties can be set to H5P_DEFAULT for the default access parameters The return value is an object 1D for the open file A negative return value indicates failure This ID should be closed when the file is no longer needed by calling H5Fclose herr_t H5Fclose hid_t file_id The return value of H5Fclose is zero for success and negative for failure 4 5 2 Dataset Access In order to retrieve the data the contents of the dataset must be read into memory This is achieved by a call to the function H5LTread_dataset_ type O 57 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 herr_t H5LTread_dataset_ type hid_t loc_id hid_t dset_name type buffer yok where type can take one of the following values char short int long float double loc_id is the file ID dset_name is the name of the dataset buffer is the location in memory where the data values will be written to A negative return value indicates failure When calling H5LTread_dataset_ type it is assumed that buffer is a memory location big enough to contain all the data to be read Otherwise a memory fault will likely result To be safe we have to query the dataset for the number of data it contains and afterwards dynamically allocate enough memory with the standard function malloc see 4 5 5 Two functions are needed to determine the number of data points stored in a dataset H5LTget_datas
67. r the SEVIRI one The content is still TBD HDF Path Radiometry Resolution Enhancement Parameters Additional Information Data type H5T_IEEE_F64BE 3 64 Solar Flux Dataset Description This dataset contains the surface density of the radiative flux of reflected solar energy at the top of the atmosphere referenced at the earth reference ellipsoid surface HDF Path Radiometry Solar Flux 45 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Additional Information The earth surface can be calculated at different heights above the earth reference ellipsoid Because the surface increases with height above the reference ellipsoid the flux surface density decreases with height by a factor R R h with R the local radius of the reference ellipsoid and h the height above the reference ellipsoid Quantisation factor 0 25 W m Data type H5T_STD_I16BE Error value 32767 Range 0 1500 W m 3 65 Solar Radiance Dataset Description This dataset contains the GERB measured radiance of reflected solar energy at the top of the atmosphere HDF Path Radiometry Solar Radiance Additional Information Quantisation factor 0 05 W m sr Data type H5T_STD_I16BE Error value 32767 Range 0 500 W m sr 3 66 Spectral Regression Parameters Dataset Description This dataset contains the spectral regression parameters that have been used to estimate unfiltered r
68. r Instrument Identifier Additional Information Data type H5T_STD_I32BE 3 51 Type Attribute Description Indicates which one of two possible imager types has been used SEVIRI or ME TEOSAT HDF Path Imager Type Additional Information Data type H5T_C_S1 3 52 RMIB Group Description This group contains information about the RMIB GERB processing software 41 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 HDF Path RMIB Additional Information None 3 53 Software Identifier Attribute Description Version number of the RMIB GERB processing software that has been used HDF Path RMIB Software Identifier Additional Information Data type H5T_C_S1 3 54 Product Version Attribute Description Version number of the RMIB GERB processing products HDF Path RMIB Product Version Additional Information Data type H5T_STD_I32BE 3 55 Radiometry Group Description This group contains information about the radiometric measurements of GERB HDF Path Radiometry Additional Information None 42 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 56 Longwave Correction Dataset Description The longwave correction factor is the ratio between the GERB measured synthetic longwave filtered radiance and the estimation of the same quantity from the imager data If this ratio is out
69. rent diameter of earth in grid lengths in x direction HDF Path Geolocation Rectified Grid dx Additional Information Units Grid length Data type H5T_IEEE_F64BE 3 32 dy Attribute Description Apparent diameter of earth in grid lengths in y direction HDF Path Geolocation Rectified Grid dy Additional Information Units Grid length Data type H5T_IEEE_F64BE 3 33 Resolution Flags Group Description This group contains the north south and the east west resolution at nadir subsatel lite point of the used rectified grid 35 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 HDF Path Geolocation Rectified Grid Resolution Flags Additional Information None 3 34 East West Attribute Description The east west resolution at nadir subsatellite point of the used rectified grid HDF Path Geolocation Rectified Grid Resolution Flags East West Additional Information Units Degree Data type H5T_IEEE_F64BE 3 35 North South Attribute Description The north south resolution at nadir subsatellite point of the used rectified grid HDF Path Geolocation Rectified Grid Resolution Flags North South Additional Information Units Degree Data type H5T_IEEE_F64BE 3 36 Nominal Satellite Longitude Attribute Description The nominal satellite longitude HDF Path Geolocation Nominal Satellite Longitude Additi
70. rt int long float double loc_id is the file ID obj_name is the name of the object that the attribute is attached to dset_name is the name of the attribute buffer is the location in memory where the attribute value will be written to A negative return value indicates failure 4 5 4 Data Types One of the aims of HDF is portability meaning that files can be created on one computer and read on another This is not obvious for binary files if the memory layout of multi byte data differ in the two machines little endian vs big endian format But the HDF library takes care of the conversion Nevertheless when reading values from an HDF file the memory data type must be supplied as one of the arguments to H5Dread or H5Aread This is so because the memory data type must be compatible with the data type stored in the HDF file for the library to be able to perform the conversion For example the library will automatically convert from signed big endian two byte integer as stored in the HDF file to a signed four byte little endian memory type but trying to retrieve float data as stored in the HDF file into an integer memory data type will generate an error Number Data The following table indicates memory data type ID the value of ar gument mem_type_idin the read functions compatible with the given stored data type the third column indicates the corresponding C types the type of argument buffer Data T
71. se to 50 km 2 2 Name Convention The file names of the L2 RMIB GERB Products are made up of several parts separated by underscore characters and an extension The first part indicates which GERB instrument produced the original raw data The GERB 1 instrument is identified by q1 The second part indicates which imager instrument produced the original raw data Instrument identifiers are SEV1 MS7 where the first one is for SEVIRI 1 and the last for Meteosat 7 imager The next identifier specifies the product type For Level 2 0 products this can be 115 for SEVIRI and 30 for Meteosat 7 25x5 for SEVIRI and 3x3 Meteosat 7 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 L20A L209 L20L L200 L20G where the last letter indicates that the product is concerned with either solar ra diation S thermal radiation L or both A or geolocation information G In addition the last letter C can be used for imager count images TBC The next part s specifies the product subtype This is one of the following 15M_50 30M_50 H where 15M 30M stands for exact 15 30 minute bins average 50 for GERB resolution and H for high resolution An optional field indicates if the geographic region covered is different from the full Earth disk Currently this can be EUROPE A referen
72. side a defined range the limit of the range is applied see 3 57 and 3 58 HDF Path Radiometry Longwave Correction Additional Information e The synthetic longwave filtered radiance is defined the total filtered radiance minus the factor A times the short wave filtered radiance Quantisation factor 0 005 Offset 1 Data type H5T_STD_I8BE Range 1 635 1 635 3 57 Longwave Minimum Correction Value Attribute Description If the longwave ratio between GERB and SEVIRI is lower than this value this value has been applied as correction HDF Path Radiometry Longwave Correction Minimum Correction Value Additional Information Data type H5T_IEEE_F64BE If no lower limit has been used this value is 1 3 58 Longwave Maximum Correction Value Attribute Description If the longwave ratio between GERB and SEVIRI is higher than this value this value has been applied as correction HDF Path Radiometry Longwave Correction Maximum Correction Value 43 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Additional Information Data type H5T_IEEE_F64BE If no upper limit has been used this value is 1 3 59 Shortwave Correction Dataset Description The shortwave correction factor is the ratio between the GERB measured shortwave filtered radiance and the estimation of the same quantity from the imager data If this ratio is outside a defined range the l
73. sizeof char Obtain the value of the Some Other Attribute attribute error H5LTget_attribute_string f_id First Group My Dataset Some Other Attribute attr_string_dyn assert error lt 0 Reading Attribute Some Other Attribute static allocation El A Obtain the value of the Some Other Attribute attribute error H5LTget_attribute_string f_id First Group My Dataset Some Other Attribute attr_string_stat assert error lt 0 Do whatever with the data retrieved from the HDF file 62 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 Here we just print it printf dynamic version n for n 0 n lt num_dims n printf Size of dimension d is d n n int dims n for i 0 i lt dims 0 i for j 0 j lt dims 1 j printf dt data i dims 1 j printf Na printf 16 Wn attr_double printf 4 s n attr_string_dyn printf static version n for i 0 i lt dims 0 i for j 0 j lt dims 1 j printf dt data_stat i j printf Na printf 16 Wn attr_double printf sYn attr_string_stat Clean up free data free dims free attr_string_dyn return 0 When this program has been compiled it should produce the output given in figure 4 4 6
74. t file_id gt 0 Check that it is a string and obtain the number of characters in the attribute value error H5LTget_attribute_info file_id File Creation Time NULL amp type_class amp attr_string_size assert error lt 0 amp amp type_class H5T_STRING Allocate enough memory to contain the string attr_string_value char malloc attr_string_size sizeof char Obtain the value of the File Creation Time attribute error H5LT get_attribute_string file_id File Creation Time attr_string_value assert error lt 0 Close the HDF file error H5Fclose file_id assert error 0 Print the attribute string to standard output printf The file s was created on s UTC time n file name attr_string_value Release memory free attr_string_value return 0 69 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 A 4 String List The following code retrieves a series of string attributes whose names are strings representing numbers The source code file name is read_rgp_string_list c include lt stdio h gt include lt stdlib h gt HDF5 Library header file tt include lt hdf5 h gt tt include lt H5LT h gt The assert macro is used to detect any error and exit from the program in case something went wrong include lt assert h gt de
75. tellite Longitude 36 PSF Parameters 45 Imager 41 Imager Instrument Identifier 41 Imager Type 41 RMIB 41 RMIB Software Identifier 42 RMIB Product Version 42 Radiometry 42 Radiometry Resolution Enhancement Parameters 45 Radiometry Shortwave Correction 44 Radiometry Solar Radiance 46 Radiometry Solar Flux 45 Radiometry Spectral Regression Parameters 46 Radiometry A Values per GERB detector cell 47 Radiometry C Values per GERB detector cell 48 Scene Identification 48 Scene Identification Cloud Amount 49 continued on next page 18 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB continued from previous page Scene Identification Cloud Cover 49 Scene Identification Cloud Phase 49 Scene Identification Surface Type 50 Scene Identification Solar Angular Dependency Models Set Version 51 Times 52 Times Start of Integration 53 Times End of Integration 52 2 3 9 lt GERB_ID gt _ lt IMAGER_ID gt _L20G_15M_50_ lt DATE gt _ lt VERSION gt hdf This product contains the geolocation latitude longitude for the pixels of the L20L_15M_50 and L20S_15M_50 products 2 3 10 Table 10 Hierarchical structure of the product L20G_15M_50 Access Path Name Page File Creation Time 25 File Name 25 GERB 28 GERB Instrument Identifier 28 Geolocation 29 Geolocation Latitude 30 Geolocation Longitude 31 Geolocation Recti
76. ts Files 2 1 Introduction This section introduces the various L2 RMIB GERB Products There are eleven 11 of them differing in contents and or resolution Each product is stored in a separate HDF file The products are divided in three main types A product type is defined by a given temporal sampling and spatial resolution e An Averaged Rectified Geolocated ARG product is defined as a 15 minute average obtained by averaging three consecutive GERB measurements The product has GERB spatial resolution 256x256 geolocated on the Rectified Grid computed by RAL cf L1 5 ARG product The spatial shape of one pixel is the average of the three GERB footprints that have contributed to it e A Snapshot High resolution Image SHI product is defined as a snapshot at imager acquisition times The product has 3x3 pixels spatial resolution 1237x1237 for SEVIRI and 833x833 for Meteosat A Binned Averaged Rectified Geolocated BARG product is defined as an av erage over a time period The period is an exact imager complete scan period 1 The first average is computed centered on 00 00 UTC The product has roughly GERB spatial resolution i e the pixels are geolocated on a rectified grid and are an average of SHI pixels from a high resolution image the grid resolution is 247x247 for SEVIRI and 277x277 for Meteosat The spatial shape of one pixel is an exact square at nadir The dimension of this square is the GERB sampling distance i e clo
77. ype Stored in HDF File Memory Data Type C Type H5T_IEEE_F64BE H5T_NATIVE_DOUBLE double H5T_STD_I16BE H5T_NATIVE_SHORT short H5T_STD_U8BE H5T_NATIVE_UCHAR unsigned char H5T_STD_I8BE H5T_NATIVE_CHAR char Character String Attributes The C language uses the term char to represent one byte numeric data and does not make character strings a first class datatype HDF5 makes a distinction between integer and character data and maps the C signed char H5T_NATIVE_CHAR and unsigned char H5T_NATIVE_UCHAR datatypes to the HDF5 integer type class When the value of an attribute is a character string to be able to allocate memory to fit the whole string we must know its length Actually the string length is stored by the library as a part of the type information The size of a string can be retrieve using the following function H5LTget_attribute_info herr_t H5LTget_attribute_info hid_t loc_id const char obj_name const char attr_name hsize_t dims H5T_class_t type_class size_t type_size ie 59 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 where loc_id is the file ID obj_name is the name of the object that the attribute is attached to attr_name is the name of the attribute dims is NULL type_class is the location in memory where the class identifier will be written to should be H5T_STRING for a string type_size is the location in memory where the size of the string will be written
78. zimuth Dataset Description See figure 1 The relative azimuth angle is the angle of the satellite observation plane relative to the principal plane The target is the observed scene on the surface of the earth characterised by its geodetic geolocation parameters The zenith direc tion is the local geodetic vertical direction The satellite observation plane contains the zenith and the satellite The principal plane contains the zenith and the sun HDF Path Angles Relative Azimuth Additional Information Quantisation factor 1 degree Data type H5T_STD_I16BE Error value 32767 Range 180 180 26 Royal Meteorological Institute MSG RMIB GE UG of Belgium GERB Version 1 2 3 9 Viewing Azimuth Dataset Description See figure 1 The viewing azimuth angle yje is the angle of the satellite observation plane relative to the zenith north plane The target is the observed scene on the surface of the earth characterised by its geodetic geolocation parameters The zenith direction is the local geodetic vertical direction The satellite observation plane contains the zenith and the satellite The zenith plane contains the zenith and the local north direction HDF Path Angles Viewing Azimuth Additional Information Quantisation factor 1 degree Data type H5T_STD_I16BE Error value 32767 Range 0 360 3 10 Solar Zenith Dataset Description See figure 1 The solar zenith angle 0 is th

L2 RMIB GERB Products User Guide - NCEO

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