Soil Moisture Retrieval Using a Two-Dimensional L-Band Synthetic Aperture Radiometer in a Semiarid Environment

摘要

Surface soil moisture was retrieved from the L-band radiometer data collected in semiarid regions during the Soil Moisture Experiment in 2004. The 2-D synthetic aperture radiometer (2D-STAR) was flown over regional-scale study sites located in AZ, USA, and Sonora, Mexico (SO). The study sites are characterized by a range of topographic relief with a land cover that varies from bare soil to grass and scrubland and includes areas with high rock fraction near the soil surface. The 2D-STAR retrieval of soil moisture was in good agreement with the ground-based estimates of surface soil moisture in both AZ $(hbox{rmse} = 0.012 hbox{m}^{3} hbox{m}^{-3})$ and SO $(hbox{rmse} = 0.011 hbox{m}^{3} hbox{m}^{-3})$. The 2D-STAR also showed a good performance in the Walnut Gulch Experimental Watershed $(hbox{rmse} = 0.014 hbox{m}^{3} hbox{m}^{-3})$ where the surface soil featured high rock fraction was as high as 60%. Comparison of the results with the Polarimetric Scanning Radiometer at the C- and X-band data indicates the superior soil moisture retrieval performance of the L-band data over the regions with high rock fraction and moderate vegetation density.