Simulations of the meteosat visible sensor response to changing boundary conditions

Abstract

Computational experiments have been conducted to simulate the METEOSAT visible sensor's response to varying surfaces and clear-sky atmospheric conditions, as a function of solar zenith angle. The possible bias in observations obtained with this limited spectral response sensor, was assessed. The filtered clear-sky planetary albedo, as observed with the METEOSAT was compared with the (0.305 - 2.5 μm) unfiltered planetary albedo, under the same environmental conditions. Four cases of wavelength-independent surface albedo (0%, 10%, 20%, 30%) and four cases of realistic wavelength dependent surface albedo (snow; meadow; dry sand; water) have been simulated. The complexity of the narrow/broadband spectral relationship of the clear-sky planetary albedo has been demonstrated. The simulations have shown that while under certain assumptions the two were in close agreement, the relationship would strongly depend on the assumptions made on the spectral dependence of the surface reflectivity.