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GOME-1 surface LER database

 
   
 
European Space Agency

page last modified:
20 January 2017
     

Robert Koelemeijer has created a surface albedo database that contains the minimum Lambertian-equivalent reflectivity values at eleven 1-nm wide wavelength bins. The Lambertian-equivalent reflectivities (LERs) were derived from GOME-1 data using the Doubling-Adding KNMI (DAK) polarised radiative transfer code. The model consists of an atmosphere for which Rayleigh scattering and ozone absorption is taken into account, and which is bounded below by a Lambertian surface. You can read Robert Koelemeijer's readme.txt file for more details.

If you're planning to use this database, please refer to the scientific paper describing the database, which is available as a PDF file (2.7 MB).


Some examples of the database:

Examples of the GOME-1 surface LER: for 4 different wavelength bands (left) and for 4 different months (right).

Surface albedo improvements at 758 and 772 nm:

This improved surface albedo database is based on the original surface albedo database created by Koelemeijer et al. (2003) which has a 1°×1° spatial resolution. The surface albedo grids at 758 and 772 nm were refined to a spatial resolution of 0.25°×0.25° at coastlines. Because of absorbing aerosol over desert areas, the retrieved surface albedo over these areas is lower than its real value. This problem was corrected by increasing the surface albedo over desert areas by 20% (Fournier et al., 2006). These improvements were only applied to the surface albedos at 758 and 772 nm, not to the other wavelength bands.


Archive:

The database, consisting of a large number of files (196 kB each), was originally put together in one large file, together with a PostScript image of the data. The large file containing the entire database can be downloaded below. For more convenient downloading, the database has also been split up into 11 zip-files, one per wavelength. Each of these files contains the following files:

  • sacspecTOTL[mm]_[wvl].dat
    == monthly minimum LER values for month [mm] and wavelength [wvl] nm
  • sacspecALLM[wvl].dat
    == annual minimum values for [wvl] nm
  • sacspecFLAG[wvl].dat
    == file with flags corresponding to the ALLM-file

Additionally, there are also FLAG files sacspecFLAG[mm].dat for the TOTL files, one for each month and valid for all wavelength bands. These are zipped together in a 12-th file. The reason for splitting up the database is to minimise the download effort in case you do not need the data of all wavelength bands.

Wavelength band Monthly data files (zipped) * Monthly PostScript images (zipped) *
335 nm ler335nm.zip ler335nm_ps.zip
380 nm ** ler380nm.zip ler380nm_ps.zip
416 nm ler416nm.zip ler416nm_ps.zip
440 nm ler440nm.zip ler440nm_ps.zip
463 nm ler463nm.zip ler463nm_ps.zip
494 nm ler494nm.zip ler494nm_ps.zip
555 nm ler555nm.zip ler555nm_ps.zip
610 nm ler610nm.zip ler610nm_ps.zip
670 nm ler670nm.zip ler670nm_ps.zip
758 nm ler758nm.zip
ler758nm_corr.zip ***
ler758nm_ps.zip
ler758nm_corr_ps.zip ***
772 nm ler772nm.zip
ler772nm_corr.zip ***
ler772nm_ps.zip
ler772nm_corr_ps.zip ***
for all
wavelengths
lerFLAG.zip
(145 kB; unzipped 2.4 MB)
lerFLAG_ps.zip
(765 kB; unzipped 3.7 MB)
NOTE: Use  "unzip"  or  "gunzip -S .zip"  to unzip.
 
   *)  The data files are all about 1 MB in size (unzipped 2.8 MB), the PostScript files are ~1.2 MB
(unzipped 4.4 MB), unless specified differently.
 
The original database (data and PostScript files) is also available as one large file:
ler.tar.zip (24 MB; unzipped 86 MB)
 
  **)  For this wavelength there is also a TOMS climatology available: TOMS_ler380nm.zip (286 kB)
 
***)  Improved surface albedo databases (spatial resolution 0.25°×0.25° at coastlines).

Documentation:

  • R.B.A. Koelemeijer, J.F. de Haan, and P. Stammes, A database of spectral surface reflectivity in the range 335-772 nm derived from 5.5 years of GOME observations, J. Geophys. Res. 108, 4070, doi:10.1029/2002JD002429, 2003.

  • N. Fournier, R.B.A. Koelemeijer, M. Eisinger, J.F. de Haan, and P. Stammes, Refinement of a database of spectral surface reflectivity in the range 335-772 nm derived from 5.5 years of GOME observations, Proceedings of the 2004 Envisat & ERS Symposium, ESA Special Publication SP-572, 2005. (PDF file)

  • N. Fournier, P. Stammes, M. de Graaf, R. van der A, A Piters, M. Grzegorski, and A. Kokhanovsky, Improving cloud information over deserts from SCIAMACHY Oxygen A-band measurements, Atm. Chem. Phys. 6, 163-172, doi:10.5194/acp-6-163-2006, 2006.