ERS soil moisture product validation in France

The CETP participates to the validation of satellite surface moisture products proposed by Vienna university. Two sites were selected for this validation : Villamblain and Grand Morin. For ERS product validation, we consider only one pixel (0.25° x 0.25°) over villamblain site. The Grand Morin basin is located in agricultural areas including forests and grasslands (mainly pasture land). The crop percentage may vary slightly from one year to another because of the crop rotation practiced in these agricultural regions. We note that 96% of the watershed has slopes less than 8%. 3 Time Domain Reflectometry (TDR) continuous measurements exist in the studied site in three different areas (Suizy, Voulton and Boissy). The ERS surface moisture products were compared to our ground truth measurements. The two sites are flat in a temperate region with homogenous land uses, then spatial soil moisture variability is not important. A mean filtering seems sufficient to estimate a mean soil moisture value. In order to make comparison between the ground and satellite estimations, we propose an estimation of volumetric moisture from ERS product indexes. The different comparisons show a general coherence between measurements and ERS products with a mean rms error for the different sites around 5% of volumetric moisture.