Retrieving China's surface soil moisture and land surface temperature using AMSR-E brightness temperatures

Based on the passive microwave radiative transfer equation, we developed a single-band model for retrieving surface soil moisture (m(v)) and land surface temperature (T-s) using Aqua satellite advanced microwave scanning radiometer (AMSR-E) C-band brightness temperatures (T-b) without any ancillary data. National-scale m(v) and T-s of China in 2009 were jointly mapped. The average mv and Ts retrieval errors are 0.037 g cm(-3) and 2.00K when validated by in situ measurements and approximately 0.025 g cm(-3) and 2.34K when compared with AMSR-E L3 m(v) and moderate-resolution imaging spectroradiometer daily T-s products. In particular, most m(v) and T-s estimation errors are under 0.37 g cm(-3) and 2.00K, respectively, for regions with the microwave polarization difference index (MPDI) between 0.01 and 0.05, but increased clearly larger for those with MPDI smaller than 0.01 or larger than 0.05, which are mostly dense-vegetated regions in Southwestern China or plateaus and dry deserts such as Inner Mongolia plateau, Qinghai-Tibet Plateau, Taklimakan Desert and Turpan basin. In summary, the proposed retrieval algorithm might provide a new way to monitor m(v) and T-s conditions for penetrable vegetation canopy regions, but further investigations are still needed, especially for specific plateau, desert and frozen regions.