Remote-sensing is an adequate tool for monitoring polar ice-sheets. In visible and infrared spectral ranges, the informations are coming from the upper top of the snow mantle. Following the snow optical properties modeling, its reflectance depends on its grains sizes. The aim of this thesis is to study the relationship between remote-sensing data and theoretical snow reflectances in order to calculate the snow grains size of the snow mantle surface layer. A snow grain size determination method is proposed and a sensitivity study is done to quantify the effects of various parameters : atmosphere, calibration, topography. Two theoretical models are studied and used in Antarctica and in the Alps. Simple ratios of reflectance in differents channels give promising results, and will perhaps allow an operational monitoring of the snow mantle. Moreover, in collaboration with the Centre d'Etudes de la Neige (MétéoFrance) a study of the optical properties of the snow polluted by atmospheric particules was done.
