Méthode d'inversion de l'épaisseur optique des aérosols, à partir d'images satellitaires de télédétection, basée sur un nouveau modèle d'indice atmosphérique (ATIM)

Abstract

The research objective of this thesis is to develop a method for the extraction of aerosol optical depth which is less sensitive to the level of darkness which can be ascribed to a given pixel. The ATIM (Atmospheric Index Model ) is fundamentally based on the work of Kaufman & Tanré. They demonstrated that the satellite level estimation on a vegetation index, which they called the ARVI (Atmospherically Resistant Vegetation Index ), was as sensitive to surface vegetation as the surface NDVI, but significantly less sensitive than the apparent NDVI to atmospheric variations over a large range of surface types. The starting point of our method was accordingly to hypothesise that a fairly unique relationship must exist between the ARVI and the surface NDVI over a variety of atmosphere and surface types. If this were the case, then the surface NDVI could be extracted from satellite measurements of ARVI by simpling inverting this relationship. A radiative transfer model could then be employed to extract the aerosol optical depth from iterative comparisons of the apparent and surface NDVI. The ATIM method exploits this fundamental idea as well as incorporating methodological refinements which parallel the historical refinements of the NDVI."--Résumé abrégé par UMI