First results of all-weather soil moisture retrieval from an optical/thermal infrared remote-sensing-based operational system in China

Abstract

ABSTRACTSurface soil moisture (SSM) content plays an important role in a number of physical processes involving the energy and mass exchanges between the land and atmosphere interactions. Determination of spatially complete SSM in regional scale has long been one of the most significant tasks in remote-sensing community. Although with limited penetrating ability comparing to microwave missions, optical/thermal infrared sensors can provide surface observations at finer spatial resolution. On the basis of a recently developed approach for deriving all-weather SSM content from satellite images, the present study investigates an optical/thermal remote-sensing-based operational system for mapping finer spatial resolution all-weather soil moisture content in China from the combined use of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the China Meteorological Administration Land Data Assimilation System (CLDAS) meteorological products. A preliminary evaluation of the all-weather SSM retrieval is implemented with field SSM measurements at 461 sites across China. Results show that the root mean square error (RMSE) varies from 0.053 to 0.070 m3 m−3 with an average RMSE of 0.063 m3 m−3 and an average bias of −0.018 m3 m−3 obtained on the six selected days from April to September. These first results of all-weather SSM retrieval indicate that the optical/thermal remote-sensing-based operational system has a promising perspective for mapping SSM with currently available satellite and meteorological products in regional scale. Finally, two practical recommendations with respective to improve the system inputs for producing more reliable SSM products are summarized for further developments of the optical/thermal remote-sensing-based operational system.