Abstract
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 m3/m3. This product will contribute to continuous soil moisture information on a global scale for global change studies.
Highlights
The microwave remote-sensed soil moisture generally refers to the water content contained in the upper 5 cm of soil, which serves as an important boundary condition in soil–atmosphere water transport modeling.[1,2,3] Large-scale detection of soil moisture is indicative of potential drought and could help in forecasting crop yields and helping farmers manage their irrigation systems more efficiently.[4]
To demonstrate the performance of soil moisture derived from the methodology, the brightness temperature obtained by HY-2/RM was used as the input for the single-channel algorithm (SCA) to retrieve the soil moisture for the year 2012
High-soil moisture estimates over central Africa and India in July are consistent with precipitation climatology and monsoonal effects
Summary
The microwave remote-sensed soil moisture generally refers to the water content contained in the upper 5 cm of soil, which serves as an important boundary condition in soil–atmosphere water transport modeling.[1,2,3] Large-scale detection of soil moisture is indicative of potential drought and could help in forecasting crop yields and helping farmers manage their irrigation systems more efficiently.[4] It may serve as a warning for flooding[5] if the soil has become too saturated to hold any further water. Microwave remote sensing has been proven to be the most effective tool to monitor the surface soil moisture at a global scale.[6] This is based on the large difference in the dielectric constant between dry soil and water. In the past few decades, various microwave sensors have been launched with a capability for monitoring
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