Soil Moisture Retrieval from Passive Microwave Data: A Sensitivity Study Using a Coupled Svat-Radiative Transfer Model at the Upper Danube Anchor Site

As passive microwave remote sensing data is sensitive to the surface soil moisture, recent satellite mission concepts, like the Soil Moisture and Ocean Salinity (SMOS) mission, to measure the surface soil moisture content with L-band passive microwave sensors will provide global soil moisture information with a high temporal resolution of about 1-3 days. In contrast, the spatial resolution used for the retrieval of the soil moisture from SMOS images will be rather coarse, in the order of tens of kilometres. The provided soil moisture information is therefore integrated over a large area that may be composed of different land covers and soils. Uncertainties of the soil moisture retrieval depend on the accuracy and spatial resolution of ancillary data, like land use information data, which is necessary for the retrieval. The sensitivity of the retrieval to different land cover information datasets is investigated, using a coupled SVAT-radiative transfer-model comparing the standard land use map used within the SMOS Level 2 soil moisture processor with a well established map for the study area. The used approach shows big differences of the retrieval in some parts of the study area while in others the retrieved soil moisture is nearly the same with both land cover maps used.