GOME-1 surface LER database

Robert Koelemeijer has created a surface albedo database that contains the minimum Lambertian-equivalent reflectivity (LER) values at 11 one-nm wide wavelength bins. The surface LER values 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 file for more details.

An alternative for the GOME-1 surface LER database is the SCIAMACHY surface LER database. This database is based on SCIAMACHY mission data and as a result offers a higher quality in terms of stability, residual cloud contamination, and spatial resolution near coastlines.

Validation of the GOME-1 surface LER climatology based on direct intercomparison with the SCIAMACHY, OMI, and GOME-2 surface LER climatologies is described here.

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

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. (PDF file)

• 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. (PDF file)

• L.G. Tilstra, O.N.E. Tuinder, P. Wang, and P. Stammes, Surface reflectivity climatologies from UV to NIR determined from Earth observations by GOME-2 and SCIAMACHY, J. Geophys. Res. Atmos. 122, 4084-4111, doi:10.1002/2016JD025940, 2017. (PDF file)