TROPOMI surface LER & DLER database

The TROPOMI surface DLER database contains the Lambertian-equivalent reflectivity (LER) of the Earth's surface at 21 one-nm wide wavelength bins between 328 and 2314 nm. Next to the traditional non-directional LER field, the database contains the directionally dependent Lambertian-equivalent reflectivity (DLER) of the surface. In the DLER, the viewing-angle dependence of the surface reflectance, due to the BRDF of the surface, is taken into account, which improves the surface reflectance considerably, especially for the longer wavelengths.

The DLER albedo values were derived from TROPOMI data using the Doubling-Adding KNMI (DAK) polarised radiative transfer code. The model consists of an atmosphere for which Rayleigh scattering and ozone absorption are taken into account, and which is bounded below by a Lambertian surface. The surface DLER is available for each month of the year and for the following wavelengths: 328, 335, 340, 354, 367, 380, 388, 402, 416, 425, 440, 463, 494, 670, 685, 697, 712, 747, 758, 772, and 2314 nm. These wavelength bands are more or less monochromatic (one nm wide in most cases) and suitable as input for the retrieval of most atmospheric species. The resolution of the database grid is 0.125°×0.125°.

Archive:

The following database based on TROPOMI observations is available:

TROPOMI_Sentinel-5P_0125x0125_surface_DLER_v2.1.nc   (15 GB)

The format and the contents of the files are explained here. The current version of the database is 2.1. This version is based on 5 years (60 months) of TROPOMI version 02.01.00 reprocessed level-1b data. Previous versions of the databases can be downloaded here.


Developments / Improvements:

Beta version 0.3 was based on 1 year of TROPOMI L1 data and only provided non-directional LER for 16 wavelength bands. Beta version 0.4 was based on 2 years of L1 data and provided LER for 17 wavelength bands. The definition of the wavelength bands was adjusted to the current 21 wavelength bands in version 0.5. The DLER was first introduced in version 0.5. Version 0.6 and version 0.7 were released after small bug fixes. Version 1.0 was the first official release, based on 3 years of collection-1 L1 data. In version 1.1 the retrieval for the snow/ice-containing field was improved. In version 2.0 filtering of scenes affected by cloud shadow was introduced. In version 2.1 the detection and handling of snow/ice contamination was improved. Versions 2.0 and 2.1 are based on 5 years of collection-3 L1 data.


Origin / Creator:

The TROPOMI surface DLER database is provided by KNMI in the framework of the Sentinel-5p+ Innovation project led by ESA. Processing was performed on the Sentinel-5P Product Algorithm Laboratory (S5P-PAL) developed and hosted by S[&]T.







 
Data use / License / Citation:

The TROPOMI surface DLER database is free to use for commercial and non-commercial purposes. If you use the database for a publication (research or otherwise), or for any other purpose, please refer to the following publication:

L.G. Tilstra, M. de Graaf, V.J.H. Trees, P. Litvinov, O. Dubovik, and P. Stammes, A directional surface reflectance climatology determined from TROPOMI observations, Atmos. Meas. Tech. 17, 2235-2256, doi:10.5194/amt-17-2235-2024, 2024 (PDF)

We suggest that you include the following acknowledgement: "We acknowledge the free use of the TROPOMI surface DLER database provided through the Sentinel-5p+ Innovation project of the European Space Agency (ESA). The TROPOMI surface DLER database was created by the Royal Netherlands Meteorological Institute (KNMI)."


Documentation:

• Algorithm Theoretical Basis Document (v2.1.0)

• Product User Manual (v2.1.0)

• Validation Report (v2.0.0)

• S5p+Innovation AOD/BRDF Final Report (v1.0)

• L.G. Tilstra, M. de Graaf, V.J.H. Trees, P. Litvinov, O. Dubovik, and P. Stammes, A directional surface reflectance climatology determined from TROPOMI observations, Atmos. Meas. Tech. 17, 2235-2256, doi:10.5194/amt-17-2235-2024, 2024. (PDF)

• L.G. Tilstra, O.N.E. Tuinder, P. Wang, and P. Stammes, Directionally dependent Lambertian-equivalent reflectivity (DLER) of the Earth's surface measured by the GOME-2 satellite instruments, Atmos. Meas. Tech. 14, 4219-4238, doi:10.5194/amt-14-4219-2021, 2021 (PDF)

• Presentation: Directional surface albedo from GOME-2 and TROPOMI (PDF)