SYNTHETIC SATELLITE RADIANCES USING THE RADIANCE SAMPLING METHOD

A statistical method to calculate the radiance at the top of the atmos phere is described. This method solves the monochromatic radiative tra nsfer equation at selected wavenumbers. A comparison with line-by-line calculations shows that the method is stable and converges to the lin e-by-line results with increasing number of selected points. The metho d has the advantage over other statistical methods that it is a strict monochromatic method, such that the exact information at the selected wavenumber is retained. This implies that overlapping absorption band s of different gases can be treated in a simple manner, which is exact at the selected wavenumbers. Since the method retains the corresponde nce of a monochromatic calculation to wavenumber, a folding of radianc e simulations with the exact filter function of a satellite sensor is easily performed. The method is applied to simulate radiances of the f uture European geostationary meteorological satellites Meteosat Second Generation and to study the possibility of cross calibration of simil ar satellite sensors aboard different satellites.