Minimize GOME Products and Algorithms
Minimize Processor Releases

Level 1

The following table reports the evolution of the GOME Level 0-to-1 GDP processor since the first operational release in 1996.


Processor
Version

ATBD

Processor updates

Operational
switch date

5.1

GOME-DLR-L1-ATBD

7A

  • New polarization correction: the Ozone climatology is replaced by Ozone column densities retrieved from GOME measurements.
  • Improved usage of dark signal measurements: calibration measurements over the South Atlantic Anomaly (SAA) are discarded during preprocessing.
  • Revised and improved spectral calibration: lamp line positions used for wavelength assignment were selected on the basis of whole-mission stability.
  • Fully calibrated products: calibration algorithms adopted by the former extraction software (gdp01_ex) are now integrated into the Level 0 to 1 processing baseline and are applied for the generation of fully calibrated Earthshine radiance and solar irradiance.
  • Updated degradation correction: the loss in throughput due to degradation of the instrument's optical components has been monitored and corrected for the entire mission.
  • Geo-location: information for each single PMD measurement is now provided.
  • Input Level 0 data: A revised master set of consolidated Level 0 files (80154 orbits) was used as input for the reprocessing campaign. The new master dataset includes ~10% of data repatriated from on-ground receiving stations and concatenated, which were of lower quality or missing in the previous dataset.
  • Cloud parameters: information retrieved with the OCRA and ROCINN algorithms have been integrated into the new Level 1 product.
  • Format and structure: The output product has been entirely revised implementing the NetCDF-4 format. Data structure is similar to EO products used for other satellite data (e.g. SCIAMACHY, Sentinel-5P). Measurements are organized in groups for modes and bands. Geo-location and other associated data are incorporated in such groups and match the measured ground pixels. Forward and backward scans are separated into different groups.

Post operational full-mission reprocessing 2017

4.03

 

6A

  • Fix to cope with increasing temperatures and changing lamp spectra properties that caused failures in the wavelength calibrations from October 2009. INITIAL file version 3.0.5.
  • Postgres tools modified to be more flexible and platform independent.
  • Added proper initialization of Cloud record.

2010

4.02

  • "Maximum Temperature Delta Allow for Search in the Spectral DB" increased from 0.6 to 6.0 to solve processing failures due to spectral calibration for temperature not found. INITIAL file version 3.0.4.
  • New functionality in the Extraction software: an input file with several radius, latitudes and longitudes or corner coordinates may be specified (option "–r" extended).

2010

4.01

  • Relaxing the limit for scan angle in cloud calculation to avoid no cloud data for polar-view measurements.
  • Checking calculated OCRA/ROCINN cloud parameters for unphysical values; which may happen under dark, low signal/noise ratio conditions. Checking and resetting values higher than limit to -1.0 is done on reading and writing Level 1 product.

2009

4.00

  • Format change: Writing now BOA (bottom of atmosphere) angles into Level 1 product.
  • Format change: Calculating OCRA/ROCINN cloud parameters and writing into Level 1 product.
  • Masking out leakage-, spectral- and PPG-calibration data measured in SAA  (South Atlantic Anomaly). Detection using PMD noise.
  • Calculating Mean Latitude and Longitude and writing to Info database.
  • New degradation routine with Lookup Table instead of polynomial fit.
  • The Extraction software is not downwards compatible to previous GDP versions.

2008

3.11

ER–TN–DLR–GO–0022
  • Land-sea-mask can now be specified in the ORDER file.
  • Fixed incorrect sun-glint detection due to wrong land-sea-mask processing.

2008

3.10

  • If no REST_ORB file provided as input, the processor reads now a state vector from an MPH of the Level 0 product. If a REST_ORB file is found this state-vector is the preferred one.
  • On some fatal errors ("Error during range check of pixel index", "Subset Counter out of range") the processor does not stop, but generates an unprocessable entry in the cat_file.

2008

3.02

  • Fixed byte swapping float values and back returned small difference in some cases.
  • All float fields in Postgres DB changed to double for better accuracy.
  • Enabled use of high-order polynomials for degradation correction.   
  • Aligned version number for processor and extractor.   

2007

3.00

  • Objectivity DB replaced by PostgreSQL.
  • Migration to Linux/GNU C++ for development and production platform.
  • Portability improved: byte swapping to and from Big Endian revised.
  • Revised spectral lines for spectral calibration.
  • New acceptance time dependent limits for sun-mean-reference rejection.
  • Functionality from GDP versions 2.30 and 2.40 included; the improved polarisation correction in the Extraction software is now default.
  • Fixed wrong extrapolation in the Extraction software degradation correction for orbits before July 1995.

2006

2.40

5B

  • New functionality in the Extraction software:

- A new correction algorithms has been implemented to recalibrate the reflectivity in channels 1 and 2, taking into account differences in degradation for the Nadir and the Sun light path (option "-F"). The parameters needed are read from the degradation-file.
- Band 1a signals have an improved correction algorithm for Peltier cross-talk.
- Experimental option to invoke an algorithm for improved polarisation
correction; recalculates p7 and improves GDF interpolation

No public release Test version for CHEOPS project

2.30

  • New functionality in the Extraction software: Two new BSDF correction algorithms have been implemented with smoothed correction parameters using a polynomial in wavelength, and with unsmoothed correction parameters read from the degradation-file.

No public release Test version for CHEOPS project

2.20

  • New functionality in the Extraction software: update spectral calibration of the Sun Mean Reference spectrum using cross-correlation with a template spectrum; option '-k' disables this feature.
  • Optimize the test to reject Sun calibrations with improper illumination (ERS-2 EBM problem starting in 17 January 2001).

2002

2.10

  • Correct geolocation of ground pixels in static view mode.
  • Close geolocation gaps. Interpolate centre coordinates of ground pixel.
  • Include a test to reject Sun calibrations with improper illumination (ERS-2 EBM problem starting in 17 January 2001).

 

2001

2.00

  • New options in the Extraction software:

- "-e" degradation correction;
- "-f" BSDF asymmetric azimuth dependency correction;
- Include scan mirror correction for albedo computation ('-a' option).

  • Reorganizing Extraction software to improve performance.

1999

1.50

4A

  • New options in the Extraction software:

- Radiance jumps correction with option "-j"

1998

1.40

  • Spatial aliasing correction using previous PMD in polarisation correction.
  • Close geo-location gaps interpolating the scan mirror positions.
  • New options in the Extraction software:

- "-r" extracts ground pixels between corners upper left and lower right;
- "-n" creates one file without sun spectrum for each ground pixel;
- Extraction software runs also under Linux operating system.

1997

1.35

  • Relax the peak selection criteria for channel 3.

1997

1.30

  • Check of scan mirror position compatible with new GOME narrow swath.
  • Changes in the Extraction software:

- FPA correction not applied when less than 61 ground pixels are available;
- New calibration option "-J" for radiance jump correction;
- Extraction software runs also under ALFA computers.

1997

1.20

  • Averaging mode recognition compatible with the new GOME calibration timelines active since 28 July 1996.

1996

1.10

  • Changes in the Extraction software:

- Saturation check done only when the co-adding mode is not active;
- New option "-a" computes albedos instead of radiances.

1996

1.00

  • FIRST OPERATIONAL VERSION

1996


Level 2

Since the release in summer 1995 of the first developmental version, Level 1-to-2 GDP was upgraded on many occasions and the quality of both O3 and NO2 products has improved significantly. The following table reports the evolution of the GOME Level 2 GDP processor, and details on configurations and the related documentation. 


Processor
Version

ATBD

Processor updates

Operational
switch date

5.0

GDP5-ATBD-1
1B

New retrieval algorithm for total ozone based on the GODFIT (GOme Direct FITting) algorithm, using a classical inverse method of iterative least squares merit-function minimization (previously DOAS).

2012
4.1  

 

 

 

 

 

2006
4.0  

 

 

 

Improved correction for ozone absorption distortion due to inelastic rotational Raman scattering; new cloud treatment; and further improvements to the AMF calculation using on-the-fly radiative transfer modelling.

2004
3.0
ER–TN–DLR–GO–002
3A

Effective absorption temperature now derived by spectral analysis; improved atmospheric databases; AMFs determined iteratively using a neural network.

2002
2.7 2B

New algorithm to account for surface inhomogeneities (albedo, ground height) in the GOME footprint. Implemented snow/ice recognition algorithm. Update of databases for O3 and NO2 cross–sections.

2000
2.4 2B  

 

1998
2.0 2A

First GDP operational version

1996