Surface albedo from space over Hapex Sahel sites

The surface albedo is important for the Earth´s energy budget. An accurate determination of this parameter is difficult to achieve over large areas because the only available measurements at this scale must be made from space. The directional behavior of the surface and the temporal variability of the atmosphere are a problem. A method has been developed in order to compute the land surface albedo from satellite measurements and has been tested over bare soil. In this study, the authors used the Hapex Sahel data and applied the same method over sparsely vegetated area. The sampling necessity, incompatible with temporal evolution of the canopy, has been satisfied by using a sliding window a few days wide to retrieve the parameters of the models for the corresponding period. The albedos were then computed using retrieved parameters to integrate the reflectance over the hemisphere