The Soil Moisture and Ocean Salinity Mission is currently in the design and development phase (Phase-B) and scheduled for launch in early 2007. SMOS will exploit an innovative instrument designed as a two-dimensional interferometer for acquiring brightness temperature observations at L-band (1.4 GHz) globally and with a revisit time less than 3 days, a spatial resolution of smaller than 50km, and with a range viewing angles (0-50 degrees) for the estimation of soil moisture and ocean salinity, both are key variables used in weather, climate and extreme-event forecasting. As a secondary objective data acquired by SMOS over ice/snow regions may prove useful to characterise the ice and snow
layers and thus complement other satellite observations to advance the science of the cryosphere (see also
A number of open scientific questions related to the physics of the signal, perturbing effects and the retrieval concept by accounting on SMOS observational characteristics needed to be addressed to prepare for the mission. In addition, appropriate campaigns were designed and organised to provide suitable data for the analysis. This included the analysis of the physics of the signal (sensitivity towards ocean salinity, soil moisture and perturbing effects), the analysis of the data product requirements of the user community and the development of retrieval concepts. Campaign activities included the WISE, LOSAC, and EuroSTARRS campaigns.
This paper is intended to summarise the activities performed so far to advance our knowledge of the microwave radiation emitted by the Earth at L-band, the capability to retrieve soil moisture and ocean salinity from it and its dependence on other factors. It will also give an outlook of future planned activities to prepare for SMOS mission.