Intercalibration of NOAA and Meteosat window channel brightness temperatures

This study presents an intercalibration of Meteosat-5 11 mu m channel and NOAA-14 10.8 mu m and 12.0 mu m channels, and their comparison for sea and land pixels. The intercalibration empirical relation is derived for clear-sky sea measurements, with similar zenith viewing angles. The root mean square difference between NOAA-14 and Meteosat-5 intercalibrated brightness temperatures is about 1.4 K (4.7 K) for all clear-sky sea (land) pixels. The discrepancies over land are analysed in terms of viewing angle, surface type, terrain elevation and exposure to sunlight. The satellite viewing geometry is responsible for two major impacts, namely: the obstruction by neighbouring clouds towards one of the satellites; and differences in surface solar illumination viewed by each sensor. It is also shown that the higher discrepancies between intercalibrated temperatures occur for the most heterogeneous surfaces (e. g. Open Shrublands). The effect of terrain variability is not linear and depends strongly on the surface type.