| Paper: | WE-A1.2 |
| Session: | Land Applications of Radiometry I |
| Time: | Wednesday, March 28, 09:20 - 09:40 |
| Presentation: |
Oral
|
| Topic: |
Soil moisture, soil state and vegetation: |
| Title: |
Parameterization of Multi-Frequency Radiometer-based Soil Moisture Retrieval Algorithm with In-situ Validation Sites |
| Authors: |
Ying Gao; University of California, Los Angeles | | |
| | Andreas Colliander; NASA Jet Propulsion Laboratory | | |
| | Mariko Burgin; NASA Jet Propulsion Laboratory | | |
| | Jeffrey Walker; Monash University | | |
| | Chunsik Chae; NASA Jet Propulsion Laboratory | | |
| | Emmanuel Dinnat; NASA Goddard Space Flight Center | | |
| | Michael Cosh; USDA Agricultural Research Service | | |
| | Todd Caldwell; University of Texas at Austin | | |
| Abstract: |
Soil moisture plays a significant role in disciplines such as hydrology, meteorology and agriculture. Over the past three decades, passive microwave remote sensing has become a widely used technique for global soil moisture estimation. In May 2002, the National Aeronautics and Space Administration (NASA) launched the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) provided by Japan Aerospace Exploration Agency (JAXA) on the Aqua satellite (ceased operation in October 2011). In 2009, European Space Agency (ESA) launched the Soil Moisture and Ocean Salinity (SMOS) mission. JAXA’s Advanced Microwave Scanning Radiometer 2 (AMSR2) onboard the GCOM-W satellite was launched in May 2012, followed by NASA’s Soil Moisture Active Passive (SMAP) mission launched in January 2015. Based on the availability of these four missions, there is an opportunity to develop a consistent inter-calibrated long-term soil moisture data record. Therefore, this study focuses on the parametrization of the tau-omega model at L-, C- and X-band using the brightness temperature (TB) observations from the four missions and the in-situ soil moisture and soil temperature data from the SMAP core validation sites across various land cover types. The same ancillary data sets as the SMAP baseline algorithm are firstly applied for retrieval at different frequencies. Then the vegetation water content (VWC) which was calculated from 10-year NDVI climatology is updated with actual MODIS NDVI measurements to see if any discrepancy exists. Preliminary comparison of SMAP and AMSR2 TB observations against forward-simulated TB at the Yanco site in Australia showed a generally good agreement with each other and higher correlation for the vertical polarization (R=0.96 for L-band and 0.93 for C- and X-band). The observed and simulated TB for the TxSON site in U.S. showed an even higher correlation of R=0.98 at vertical polarization at L-band. Simultaneous calibrations of the vegetation parameter b and roughness parameter h at both horizontal and vertical polarizations are also performed. A set of model parameters for successfully retrieving soil moisture at different validation sites at L-, C- and X-band respectively are presented. The research described in this paper is supported by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. |
