Soil Moisture Time Series from Active Radar in Support of Runoff Monitoring on Local, Catchment and Regional Scale
Bartsch, A; Pathe, C; Sabel, D; Wagner, W; Doubkova, M
Vienna University of Technology
Soil moisture is a crucial parameter for hydrological modelling. It reflects soil properties as well as hydrometeorological conditions. C-band scatterometer and ScanSAR systems have been proven suitable for the derivation of location specific near surface soil moisture variations. ERS scatterometer time series are available since 1992 and are complemented by Metop ASCAT globally since 2007. The latter also provides an improvement of spatial resolution from 50km to 25km and increased daily coverage. ENVISAT ScanSAR data in ASAR Global Mode are less frequently acquired but provide up to weekly samples on 1km resolution since December 2004.
Location specific relative soil moisture has been analysed from ENVISAT ASAR Global Mode data and ERS scatterometer data for the Okavango upper catchment and compared to river discharge. Correlations above 0.8 can be observed in subtropical climates independent on the spatial resolution of the active microwave data. Saturated surfaces which contribute to a large extent to surface runoff and thus increased river flow can be identified with the 1km ENVISAT dataset.
Metop ASCAT soil moisture will be distributed by EUMETSAT in near real time. The processing chain for ENVISAT derived soil moisture was setup within the ESA Tiger DUE Innovator project SHARE for hydrometeorological applications in the SADC region. These operational monitoring schemes provide valuable complementary information to altimeter measurements.