ESA SMOS soil moisture
| Principal investigator | Bob Su |
| Partner(s) | A. Chanzy (INRA, F), R. de Reu (VU), J.P. Wigneron (INRA, F), J.C. Calvet (CNRS/Meteofrance, F), M. Berger (ESA) |
| Funding | ESA |
| Research period | 2005 – 2010 |
Summary
Soil moisture plays important roles in climate and water resource management. In particular, it regulates the partitioning of incoming radiative energy into sensible and latent heat fluxes and governs the processes of infiltration, percolation, unsaturated zone flow and overland flow generation (and subsequently evaporation). At climate time scales, soil moisture together with sea surface temperatures is a critical boundary condition controlling fluxes to the atmosphere.
Soil moisture must be accurately represented in hydrologic and land surface models because it governs/affects the rate of overland flow generation during a rain event. Soil moisture also is a predictive factor of summer rainfall over continents in model experiments and becomes a critical forcing function for continental areas during the summer months when potential evaporation rates are at a maximum.
Several techniques hold promise for extensive (continental scale) observation of soil moisture. Remote sensing of surface layer soil moisture (or "soil wetness") has been studied extensively in the course of numerous field and/or airborne campaigns. The use of remote sensing for soil moisture has been convincingly demonstrated in terrain covered by thin or moderately dense vegetation (e.g. typical crops), using passive microwave emission radiometry at low microwave frequencies. Backscatter measurements using an active microwave sensor (scatterometer or radar system) can provide finer spatial detail, but deliver ambiguous information, as the return signal depends upon surface roughness, primarily, and soil moisture secondarily.
An L-band soil-moisture measurement mission at a 30-50 km spatial resolution could be a compromise that would provide very valuable data. Such a mission would make possible studies of many science applications that clearly demonstrate the significance of monitoring soil moisture and the European Space Agency is currently implementing the SMOS (soil moisture and ocean salinity) mission for measurement of soil moisture and ocean salinities.
The task of this project will concentrate on developing remote sensing and modelling methodologies for better estimation of soil moisture at global scale by using available and future space observations and validations of the developed methodologies using observation data from recent field experiments. The long-term global soil moisture products will be used to answer the question: if the climate warms in the future, will there be an intensification of the water cycle and, if so, what is the nature of that intensification?