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gerb_stations [2021/01/15 15:32]
gerb_stations [2022/02/15 14:58] (current)
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 +====== GERB Station Data ======
 +
 +===== Introduction =====
 +
 +At the end of the RMIB GERB processing, the data in the SHI images (3*3 SEVIRI pixel resolution) is extracted over pre-defined pixels. These pixels correspond to the positions of ground measurement stations in the GERB field-of-view such as BSRN sites. This extraction is expected to be useful in the frame of the validation of the GERB processing and to validate surface radiation budget retrieval from GERB data.
 +
 +===== Listing of stations =====
 +
 +The extraction is currently performed over the following stations:
 +
 +    Station ​      ​Country ​              ​Lat ​     Lon
 +
 +    Achern ​       Germany ​              ​48.638 ​  8.066
 +    Balbina ​      ​Brazil ​               -3.2   -60.0
 +    Bermuda ​      ​USA-sponsored ​        ​32.3 ​  -64.3
 +    Budapest ​     Hungary ​              ​47.8 ​   19.1
 +    Cabauw ​       The Netherlands ​      ​51.97 ​   4.93
 +    Cambourne ​    ​UK ​                   50.0    -5.0
 +    Carpentras ​   France ​               44.0     5.0
 +    Chilbolton ​   UK                    51.1445 -1.437
 +    De-Aar ​       South Africa ​        ​-30.7 ​   24.0
 +    Florianopolis Brazil ​              ​-27.5 ​  -48.5
 +    Hornisgrinde ​ Germany ​              ​48.604 ​  8.204
 +    Heselbach ​    ​Germany ​              ​48.539 ​  8.395
 +    Ilorin ​       Nigeria ​               8.5     4.6
 +    Lindenburg ​   Germany ​              ​52.3 ​   14.1
 +    Niamey ​       Niger                 ​13.477 ​  2.176
 +    AMMA-anc ​     Niger                 ​13.522 ​  2.632
 +    Palaiseau ​    ​France ​               48.713 ​  2.204
 +    Payerne ​      ​Switzerland ​          ​46.8 ​    6.9
 +    Riyadh ​       Saudi Arabia ​         24.7    48.8
 +    Sede-Boqer ​   Israel ​               30.9    34.8
 +    Tamanrasset ​  ​Algerie ​              ​22.78 ​   5.85
 +    Toravere ​     Estonia ​              ​58.3 ​   26.5
 +    Uccle         ​Belgium ​              ​50.8 ​    4.35
 +    Valencia ​     Spain                 ​39.57 ​  -1.29
 +
 +===== Files Format =====
 +
 +For each station, a monthly ASCII file is created (for example //​Uccle_200402.txt//​ for February 2004 at the Uccle station). The file contains a header followed by the 15' data organized in line. The file looks like:
 +
 +  # Station: Valencia
 +  # position ​     : lat=39.570 ​ lon=-1.290 ​  ​(line=187.822,​column=606.480)
 +  # nearest pixel : lat=39.549 ​ lon=-1.342 ​  ​(line= ​   188,​column= ​   606)
 +  # Viewing zenith angle=46.000000 , viewing azimuth angle=178.000000
 +  #
 +  #  time        flux_s ​ flux_t ​ rad_s  rad_t c_sw c_lw cc  ca  cp  sz  ra        hdf_file
 +  20040219075510 ​  ​81.00 ​ 230.75 ​ 97.25 371.75 ​  ​1 ​  ​3 ​ -1  -1  -1  80 117 # G2_SEV1_L20A_H_20040219_074500_V002.hdf
 +  20040219081010 ​  ​94.00 ​ 229.25 120.00 369.50 ​  ​7 ​ -1  -1  -1  -1  77 119 # G2_SEV1_L20A_H_20040219_080000_V002.hdf
 +  20040219082510 ​ 107.00 ​ 235.25 144.25 379.25 ​  ​3 ​  ​1 ​  ​0 ​  ​0 ​  ​0 ​ 74 122 # G2_SEV1_L20A_H_20040219_081500_V002.hdf
 +  20040219084010 ​ 128.00 ​ 232.25 178.50 374.25 ​  ​5 ​  ​0 ​  ​0 ​  ​0 ​  ​0 ​ 72 125 # G2_SEV1_L20A_H_20040219_083000_V002.hdf
 +  20040219085510 ​ 134.00 ​ 229.75 194.50 370.50 ​  ​8 ​ -2   ​0 ​  ​0 ​  ​0 ​ 70 128 # G2_SEV1_L20A_H_20040219_084500_V002.hdf
 +  20040219091010 ​ 149.50 ​ 228.00 214.25 367.25 ​  ​5 ​  ​0 ​ 22  14   ​0 ​ 67 131 # G2_SEV1_L20A_H_20040219_090000_V002.hdf
 +  20040219092510 ​ 169.75 ​ 234.00 253.00 377.50 ​  ​5 ​  ​1 ​ 11  11   ​0 ​ 65 134 # G2_SEV1_L20A_H_20040219_091500_V002.hdf
 +  ...
 +  ...
 +
 +The header gives:
 +
 +  - the positions of the station (lat-lon and coordinates in the ARCH field-of-view)
 +  - the positions of the nearest pixel (lat-lon and coordinates in the ARCH field-of-view)
 +  - the viewing angle for the pixel
 +  - the viewing azimuth angle for this pixel
 +
 +The different columns of data provide respectively:​
 +
 +  - Time (UTC) of acquisition at the station [YYYYMMDDhhmmss],​
 +  - solar flux [W/m2],
 +  - thermal flux [W/m2],
 +  - solar radiance [W/m2/sr],
 +  - thermal radiance [W/m2/sr],
 +  - shortwave correction factor [%],
 +  - longwave correction factor [%],
 +  - cloud cover [%],
 +  - cloud amount [%],
 +  - cloud phase [%],
 +  - solar zenith angle [°],
 +  - relative azimuth angle [°],
 +  - original file name.
 +
 +Remarks:
 +
 +  - When a quantity is not available (for example the cloud retrieval during the night) the quantity is set to -1.0.
 +  - The user must be aware that the data files are not sorted chronologically.
 +  - For more information about the meaning of these different numbers see [[gerb_content|GERB Content Description]].
 +  - Details of BSRN sites can be found at: https://​bsrn.awi.de/​
 +
 +===== Station data access =====
 +
 +The station data are available for download on the ROLSS FTP site provided you are a registered GERB data user (you need a //​username//​ and //​password//​ to login). The station files are in the following ROLSS directories:​
 +
 +     cd G2/​SEV1/​G2_SEV1_L20A_H_STATION ​      ​before May 2007
 +     cd G1/​SEV2/​G1_SEV2_L20A_H_STATION ​      after May 2007
 +
 +===== For more information / addition of station =====
 +
 +For additional information or to add new locations in the list, please email:
 +
 +  * To : <​Nicolas.Clerbaux@meteo.be>​
 +  * CC : <​gerb@oma.be>​