Calibration of Roughness Parameters Using Rainfall-Runoff Water Balance for Satellite Soil Moisture Retrieval

摘要

Soil moisture is an important component in hydrologic and meteorologic processes. Remote sensing devices, such as satellite radiometers, are useful tools to obtain soil moisture information over a large region. However, effective "ground truth" calibration data for satellite sensors are lacking. This paper presents a new approach on the basis of rainfall and river runoff hydrologic data to estimate satellite-based soil moisture. The catchment water storage change from the rainfall and river runoff has a strong link with the soil moisture information and the parameterization of the surface roughness parameters h and Q. The proposed methodology is tested at the Brae catchment in southwest England. Two years of satellite data are used for calibrating and retrieving surface soil moisture, and 1 year of data is used for validation. This study indicates that the estimated daily soil moisture from satellite correlates well with the flow observations after applying the new calibration method, and good agreement (R~2 = 0.74) is shown between the water storage change and the soil moisture change. The results indicate that this new scheme could be a useful approach in improving the satellite soil moisture retrieval for hydrologic applications.