Monitoring space-time soil wetness variations by a multi-temporal microwave satellite records analysis

In the last few years, remote sensing observations have become an useful tool for providing hydrological information, including the quantification of the main physical characteristics of the catchments, such as topography and land use, and of their variables, like soil moisture or snow cover. Moreover, satellite data have also been largely used in the framework of hydro-meteorological risk assessment and mitigation. Recently, an innovative Soil Wetness Variation Index (SWVI) has been proposed, using data acquired by the microwave radiometer AMSU (Advanced Microwave Sounding Unit), flying aboard NOAA (National Oceanic and Atmospheric Administration) polar satellites. The proposed index, developed by a multi-temporal analysis of AMSU records, seems able to reduce the problems related to vegetation and/or roughness effects. Such an approach has been tested, with promising results, on the analysis of some flooding events which occurred in Europe in past years. In this paper, preliminary results obtained by the analysis of data related to the flooding event occurred in Europe during April 2006 are presented. Preliminary outcomes achieved seem to demonstrate the efficiency of the proposed indicator in detecting soil wetness variations in the space-time domain without the need of auxiliary or ancillary information.