Satellite estimation of solar irradiance at the surface of the earth and of surface albedo using a physical model applied to Meteosat data.

Abstract

A physically based model is used to derive downward solar irradiance at the surface of the earth and surface albedo from Meteosat satellite measurements in the wavelength range between 0.40 and 1.0 micro m. The model takes into account Rayleigh and Mie scattering, water vapor and ozone absorption. No threshold setting is necessary to distinguish between clear and cloudy conditions, thereby avoiding the problem of its arbitrary nature and to some extent allowing quicker and easier data processing. Comparison of noontime satellite estimates with analogous hourly solar irradiance measurements obtained from the French pyranometer network shows a correlation coefficient of 0.92 and a rms error of 109W m-2 (20% of the mean solar irradiance). The maximum error occurs for values of insolation around 300W m-2 and can be mostly attributed to the different spatial and temporal samplings of the systems being compared.-from Authors