A long term data acquisition effort of profile soil moisture is under way in southwestern France at 12 automated weather stations. In this paper, both those in situ measurements and a synthetic data set covering continental France are used to test a simple method to retrieve root zone soil moisture from a time series of surface soil moisture information. A recursive exponential filter using a time constant, T, is used to compute a soil water index. A unique T value equal to 6 days, estimated after comparing the retrieved soil water index with the observed values at a depth of 30 cm, presents a satisfactory correlation for all stations. The surface soil moisture observed at 5 cm is used to evaluate the normalized surface soil moisture estimates derived from coarse resolution (25 km) active microwave data of the ASCAT C-band scatterometer instrument (onboard METOP) for a period of 6 months (April-September) in 2007. For 10 stations, significant correlation levels are found for either the whole pooled data set or for a part of them function of the localisation. The best correlation between a soil water index derived from ASCAT and the in-situ observations is obtained for a T-value of 14 days.
|Translated title of the contribution||Use of in-situ soil moisture measurements to evaluate microwave remote sensing products in south-western France|
|Number of pages||7|
|Journal||La Houille Blanche|
|Publication status||Published - May 2010|