Treball confidencial fins el 19/07/2015The improvement in weather forecast and climate motorization, to prevent for example
natural disasters, requires global scale knowledge of the soil moisture (SM) and the surface
salinity (SSS), which are non-existent at present due to the difficulty to carry out in-situ
measurements. These parameters influence the heat exchange among land, sea and air. On one
hand, thanks to the SM, the amount of water on Earth and the exchange of energy between the
land’s surface and the atmosphere can be known. On the other hand, the knowledge of the
distribution of the SSS will inform about sea currents and differences between evaporation and
precipitation. The quantification of these parameters will contribute to improve the weather
forecasts, hydrological studies, vegetation motorization, and risk of forest fires.
As part of the program “The living planet programme: Earth Explorer Opportunity
Missions”, the European Space Agency (ESA) selected in 1999 the Soil Moisture and Ocean
Salinity (SMOS) mission, designed to observe soil moisture over land and salinity over the
oceans. It was launched in 2009 and has put in orbit the first microwave imaging radiometer
using aperture synthesis. Over the sea, sea surface salinity will be remotely measured by means
of L-band (1400-1427 MHz) microwave radiometry. As the brightness temperature also depends
on the sea surface temperature and on the sea state, post-processing corrections are needed to
get the surface salinity. Over land, soil moisture is retrieved from the changes in the L-band
brightness temperature, although post processing correction for surface roughness and
vegetation are also required
