The objectives and rationale of the Soil Moisture and Ocean Salinity (SMOS) mission

This paper will describe the SMOS concept in terms of instrument (characteristics) investigates the main aspects of the retrieval capabilities of the 2D microwave interferometer for monitoring soil moisture, vegetation biomass and surface temperature. The analysis is based on model inversion taking into account the instrument characteristics. The standard error of estimate of the surface variables is computed as a function of the sensor configuration system and of the uncertainties associated with the spatial measurements. The inversion process is based on a standard minimization routine that computes both retrieved variables and standard error associated with the retrievals. The potential of SMOS, depending on the view angle configuration and the use of the sole 1.4 GHz is investigated. The analysis investigates the possibility to retrieve one, two or the three surface variables, depending on the system configuration. These questions are key issues to define the observation configuration of SMOS that meets the scientific requirements and the technical constraints of the spatial missions