Potential soil moisture product from the Chinese HY-2 scanning microwave radiometer and its initial assessment

The Chinese HY-2, a satellite designed for ocean dynamic environment monitoring, was launched on August 16, 2011. The onboard scanning microwave radiometer (RM) is primarily designed for sea surface temperature and wind speed mapping. However, our objective of this investigation is to exploit the large amount of land observations of RM and to extend the mission scope to the retrieval of surface soil moisture, which is also an essential boundary condition for coupling with atmospheric dynamics. The single-channel algorithm (SCA) was implemented using only the RM observed brightness temperature to estimate the surface soil moisture. Ancillary data of a normalized difference vegetation index were processed and used as inputs for the SCA to calculate the vegetation water content, which is a required parameter for estimating the vegetation optical depth. The retrieved soil moisture results agree with the global climate pattern of wet and dry regions. Initial assessments were performed using soil moisture measurements by in situ underground sensors over two selected networks: REMEDHUS in Spain and CTP-SMTMN network over the Tibetan Plateau. Results showed a good performance of soil moisture estimation for these land surface conditions for the year 2012, with the lowest root mean square error of 0.047 m∕m. This product will contribute to continuous soil moisture information on a global scale for global change studies. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. [DOI: 10.1117/1.JRS.8.083560]