|Date of Launch:|
|ERS-1 - 17 July 1991
ERS-2 - 21 April 1995
|ERS-1 ended on March 2000 and ERS-2 September 2011|
|782 to 785 km|
|Near-circular, polar, Sun-synchronous|
GOME Level 1 products contain Earthshine radiance at the Top of the Atmosphere and solar irradiance spectra as raw detector signals (binary Analog to Digital Converted units) of the science measurements plus calibration constants. Level 1 products were generated by DLR on behalf of the European Space Agency with GOME Data Processor (GDP) version 4.0 starting from Extracted GOME Calibration Level 0 data files (EGOC).
The Level 1 data product includes a header, fixed calibration data, ground-pixel specific calibration parameters, and GOME science data in ten spectral bands. With the different integration times, these bands (six spectrum bands, because channel 1 and 2 are divided into two electronically independent bands; three 'stray light' bands; one 'blind' band) are handled as separate logical units of data. The header includes reference to input data, processing software and pre-flight data versions, time correlation, and orbital information. The fixed calibration data includes leakage current, and noise characteristics, spectral, and radiometric calibration parameters, sun reference spectra, and polarisation sensitivity parameters. The pixel specific calibration parameters include geo-location information, seven fractional polarisation values, and header information retained from the Level 0 data.
The Level 1 products are generated and released in a sort of compressed format (they contain calibration data plus raw signals as 2-byte integers). The end user has to apply an "extraction" software tool to obtain the final Level 1 data (fully calibrated signals as 4-byte floats plus three 4-byte floats for wavelength, accuracy error and precision error). Using the included calibration data, the ADC readings of the diode arrays in the individual band data records are converted to geo-located, spectrally and radiometrically calibrated radiances, including the correction for polarisation, leakage current and stray light.
The Extraction Program (gdp01_ex) developed by DLR for version 4.00 data is available on the product FTP-site in the directory "programs/level_1/".
|Conversion to Engineering Units||Polynomial coefficients of analog data package measurements and other semantic explanations of the data package content|
|Correction for Straylight||Centre pixels of ghost columns, their efficiencies and defocussing|
|Radiometric Calibration||Bi-directional scattering distribution function of the diffuser in the calibration unit, Instrument response function, Polarisation characteristic of the calibration unit|
|Polarisation Correction||Polarisation sensitivity per pixel, Correction factor for the polarisation sensitivity per pixel to correct for the various scan mirror,positions, Wavelength dependency of the PMDs, the PMD ratios. In-flight calibration data (Leakage current correction, Pixel-to-pixel gain information, Spectral calibration parameters, Sun reference spectra measurements)|
90 N, 90 S, 180 W, 180 E
|Temporal coverage:||1995-06-27 - 2011-07-03
Sporadic data since July 2003 due to problems with tape recorder on ERS-2
|Current Processor Version:||GDP 4.0|