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Improved MERIS cloud detection

Rene Preusker(1), Jürgen Fischer(1), Anja Hünerbein(1), Carsten Brockmann(2), Marco Zühlke(2) and Uwe Krämer(2)

(1) FU Berlin, Carl-Heinrich_Becker-Weg 6-10, 12165 Berlin, Germany
(2) Brockmann Consult, Ottilie-Baader-Str. 15, 21035 Hamburg, Germany

Abstract

We will present a new cloud detection scheme for MERIS, developed and compiled in the framework of ESA's ALBEDOMAP project which demanded a much better cloud detection than the standard MERIS L2 scene identification provides. However, since MERIS measures reflectance in 15 channels between 400nm and 1000nm only, the very valuable thermal information (e.g. at 11µm) and the information from the liquid and ice water absorption (e.g. at 1.6µm) are not available. The cloud detection for MERIS must therefore rely on the obvious cloud brightness and cloud “whiteness". Additionally i) the mean scattering height, using the oxygen absorption band (channel 11), ii) a weak absorption feature of snow at 0.9µm and iii) the very low albedo of most natural surfaces at 0.4µm have been utilized to improve the cloud detection significantly. We will present this cloud and snow detection scheme, results of first validation activities. Also two additional temporal filters have been implemented, which are very valuable for the detection of partly cloudy pixels and are applicable for any kind of time series and averages.

 

Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry