Soil moisture-runoff relation at the catchment scale as observed with coarse resolution microwave remote sensing

摘要

Microwave remote sensing offers emerging capabilities to monitor globalhydrological processes. Instruments like the two dedicated soil moisturemissions SMOS and HYDROS or the Advanced Scatterometer onboard METOP willprovide a flow of coarse resolution microwave data, suited for macro-scaleapplications. Only recently, the scatterometer onboard of the European RemoteSensing Satellite, which is the precursor instrument of the AdvancedScatterometer, has been used successfully to derive soil moisture informationat global scale with a spatial resolution of 50 km. Concepts of how tointegrate macro-scale soil moisture data in hydrologic models are howeverstill vague. In fact, the coarse resolution of the data provided by microwaveradiometers and scatterometers is often considered to impede hydrologicalapplications. Nevertheless, even if most hydrologic models are run at muchfiner scales, radiometers and scatterometers allow monitoring ofatmosphere-induced changes in regional soil moisture patterns. This may proveto be valuable information for modelling hydrological processes in largeriver basins (>10 000 km2. In this paper, ERS scatterometer derivedsoil moisture products are compared to measured runoff of the Zambezi Riverin south-eastern Africa for several years (1992–2000). This comparisonserves as one of the first demonstrations that there is hydrologic relevantinformation in coarse resolution satellite data. The observed highcorrelations between basin-averaged soil moisture and runoff time series(R2