A directional surface reflectance climatology determined from TROPOMI observations

• Published in: Atmospheric measurement techniques 2024-04, Vol.17 (7), p.2235-2256
• Main Authors: Tilstra, Lieuwe G, de Graaf, Martin, Trees, Victor J. H, Litvinov, Pavel, Dubovik, Oleg, Stammes, Piet
• Format: Article
• Language: English
• Subjects: Aerosols; Albedo; Algorithms; Anisotropy; Atmosphere; Calibration; Climate science; Climatology; Distribution functions; Earth surface; Equator; MODIS; Nitrogen dioxide; Ocean, Atmosphere; Oceans; Parameterization; Polar orbiting satellites; Reflectance; Satellite instruments; Satellite observation; Satellites; Sciences of the Universe; Shadows; Short wave radiation; Spatial discrimination; Spatial resolution; Viewing; Wavelength
• ISSN: 1867-8548; 1867-1381; 1867-8548
• DOI: 10.5194/amt-17-2235-2024

In this paper, we introduce a spectral surface reflectivity climatology based on observations made by TROPOMI on board the Sentinel-5P satellite. The database contains the directionally dependent Lambertian-equivalent reflectivity (DLER) of the Earth's surface for 21 wavelength bands ranging from 328 to 2314 nm and for each calendar month. The spatial resolution of the database grid is 0.125° x 0.125°. A recently developed cloud shadow detection technique is implemented to avoid dark scenes due to cloud shadow. In the database, the anisotropy of the surface reflection is described using a third-order parameterisation of the viewing angle dependence. The viewing angle dependence of the DLER is analysed globally and for a selection of surface type regions. The dependence is found to agree with the viewing angle dependence found in the GOME-2 surface DLER database. Differences exist, related to the actual solar position. On average, the viewing angle dependence in TROPOMI DLER is weaker than for GOME-2 DLER, but still important.