Problems related to the determination of land surface parameters and fluxes over heterogeneous media from satellite data

Satellites will be important tools for climatological research and observations when the means to determine land surface parameters and fluxes from their radiances become operational. In order to achieve this goal, it is necessary to derive adequate models which relate the fluxes to the measured radiances and to invert these models. However, while this determination is relatively straight-forward for homogeneous media, this is not the case for vegetated areas and heterogenous surfaces, which make up the IFOV of most satellites. This paper presents a discussion of the problems encountered in the definition of relevant parameters which can describe heterogeneous media as a whole and will tentatively give a procedure to extent the definition of parameters from local to regional scales via inversion of appropriate models. The discussion addresses the adequacy, which appears possible, of these models for describing physical processes at the Earth/atmosphere interface as observed with satellite systems.