ERRORS AT LARGE SATELLITE ZENITH ANGLES ON AVHRR DERIVED SEA-SURFACE TEMPERATURES

The study presented here is a part of an attempt to improve the operational algorithm used at the Centre de Meteorologie Spatiale (CMS) to calculate Sea Surface Temperature (SST) from Advanced Very High Resolution Radiometer (AVHRR) data. The errors produced by SST retrieval algorithms are analysed through two experiments: an examination of thc errors calculated on a validation file and an analysis of the temperatures of oceanic cloud-free areas seen under two distinct satellite zenith angles (theta) for consecutive night-time orbits. This Letter presents the part of thc study dedicated to the effect of large viewing angles on the retrieval of SST. Correction terms are proposed and compared, on the same set of data, to split window algorithms using theta-dependent coefficients