L-, C- and X-band passive microwave soil moisture retrieval algorithm parameterization using in situ validation sites

Ying Gao, Andreas Colliander, Mariko S. Burgin, Jeffrey P. Walker, Chunsik Chae, Emmanuel Dinnat, Michael H. Cosh, Todd Caldwell, Aaron Berg, José Martínez-Fernández

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther

2 Citations (Scopus)


Soil moisture plays a significant role in disciplines such as hydrology, meteorology and agriculture, and passive microwave remote sensing has become a widely used technique for global soil moisture estimation over the past three decades. Several satellite missions carrying radiometers have been launched over the past years. Among them are Japan Aerospace Exploration Agency's (JAXA's) Advanced Microwave Scanning Radiometer-EOS (AMSRE) launched on NASA's Aqua satellite, European Space Agency's (ESA's) Soil Moisture and Ocean Salinity (SMOS) mission, JAXA's Advanced Microwave Scanning Radiometer 2 (AMSR2) onboard the GCOM-W satellite, and NASA's Soil Moisture Active Passive (SMAP) mission. Based on the availability of these four missions, there is an opportunity to develop a consistent inter-calibrated longterm soil moisture data record. This study focuses on the parametrization of the tau-omega model for soil moisture retrieval at L-, C- and X-band using brightness temperature observations from the four missions and in-situ soil moisture and soil temperature data from the SMAP core validation sites across various land cover types. The ancillary data sets used in the SMAP baseline algorithm are used for the retrievals at different frequencies. Simultaneous calibrations of the vegetation parameter b and roughness parameter h at both horizontal and vertical polarizations are performed. A set of model parameters to successfully retrieve soil moisture at different validation sites at L-, C- and X-band are presented. A preliminary comparison of SMAP and AMSR2 soil moisture retrievals against in situ observations at the Yanco (Australia) and TxSON (U.S.) sites showed the best accuracy and correlation at L-band (RMSD=0.03-0.05 m3/m3; R=0.92-0.94). The C-/X-band performance was not as satisfactory as L-band (RMSD=0.08-0.17 m3/m3; R=0.24-0.79). This also indicates that retrieval at higher frequencies can be very challenging when dense vegetation is present.

Original languageEnglish
Title of host publication2018 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2018 - Proceedings
PublisherIEEE, Institute of Electrical and Electronics Engineers
Number of pages4
ISBN (Electronic)9781538671504
Publication statusPublished - 31 Oct 2018
EventIEEE International Geoscience and Remote Sensing Symposium 2018 - Valencia, Spain
Duration: 22 Jul 201827 Jul 2018
Conference number: 38th
https://ieeexplore.ieee.org/xpl/conhome/8496405/proceeding (Proceedings)

Publication series

NameInternational Geoscience and Remote Sensing Symposium (IGARSS)


ConferenceIEEE International Geoscience and Remote Sensing Symposium 2018
Abbreviated titleIGARSS 2018
Internet address


  • AMSR2
  • Brightness temperature
  • Passive microwave
  • SMAP
  • Soil moisture

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