Exploitation des nouvelles capacités d'observation de la Terre pour évaluer le rayonnement solaire incident au sol

摘要

The surface solar irradiance (SSI) is seldom measured and several methods have been developed for its assessment from images taken by geostationary or polar-orbiting satellites. In current methods, so-called inverse, the signal received by the satellite is inverted to derive the radiation on the ground. It is felt that as a whole, limits of such methods are presently reached in terms of accuracy. Consequently, a new paradigm is studied based on a direct modelling of propagation of solar radiation through the atmosphere. In this thesis, we design a new method -called Heliosat-4- based on the radiative transfer model libRadtran; it benefits from advanced products derived from recent earth observation missions. For this purpose, we - establish by the means of a sensivity analysis, the necessary inputs of any method based on radiative transfer model, - establish that SSI for a cloudy atmosphere can be considered as equal to the product of the SSI obtained under clear-sky and a function of the cloud extinction and ground albedo contribution, - implement approximations of radiative transfer equation, for clear and cloudy atmosphere, allowing rapid calculations. Heliosat-4 is free from empirical parameters, easy to implement and deliver simultaneously direct, diffuse components and spectral distribution of irradiance. These characteristics, while necessary for various applications, are rarely provided. The first results of the validation of the new method with ground measurements are encouraging: observed performances are similar to those of current methods.