Talk by Simon Yueh, Jet Propulsion Laboratory, CalTech: NASA Soil Moisture Active Passive Mission Status, Products, and Future Plan

Topic: Hydrology

Simon Yeah, Jet Propulsion Laboratory, CalTech


noon to 1 p.m., Oct. 11, 2023


Seminar Format

Available remotely via Zoom webinar. Contact the department to subscribe to the email list (zoom link provided in announcement).


The NASA Soil Moisture Active Passive (SMAP) Mission was launched in January 2015, and its L-band radiometer has been operational since April 2015. The key science requirements of the SMAP mission are to provide accurate soil moisture for hydrology and carbon cycle studies. The radiometer calibration has been very stable, with less than 0.2 K rms variation over eight years. The quality of baseline soil moisture products based on the Dual Channel Algorithm (DCA) has reached 0.036 m3/m3 unbiased RMSE and better than 0.8 correlation in comparison with the in-situ data from Cal/Val sites. The DCA algorithm can also produce the Vegetation Optical Depth (VOD). There is clear linearity between SMAP VOD and tree height spatially for values of tree height less than 20 m, and the relationship remains fairly linear up to tree heights of ~ 35 m with a strong correlation of 0.81. Validation studies in the US corn belt have also found a significant correlation between the SMAP VOD and the crop water content. Since 2020, the SMAP soil moisture on a polar EASE-2 grid has been developed to achieve more uniform zonal and meridional sampling in the polar regions. We have also updated the water mask derived from the NASA Terra MODIS Land Water Mask version 6 (2015-2019) record. The benefit is greater in the Northern Hemisphere high latitudes where the updated water mask is more effective in resolving the abundance of smaller water bodies in boreal and tundra wetlands, and many anomalous soil moisture retrievals (overly wet) near the coastlines have been eliminated. SMAP’s L-band data has been found useful for many scientific applications, including depictions of water and carbon cycles, improvement to parameterization of hydrologic processes over land surfaces, flood forecasting, and ocean surface salinity mapping. The uncertainty of the current soil moisture products will be described. There are five high-priority tasks to be conducted during the next mission extension phase (2024-2026). Highlights of the future plan will be provided.


Simon H. Yueh received a Ph.D. degree in Electrical Engineering in January 1991 from the Massachusetts Institute of Technology. He was a postdoctoral research associate at the Massachusetts Institute of Technology from February to August 1991. In September 1991, he joined the Radar Science and Engineering Section at the Jet Propulsion Laboratory (JPL). He was the supervisor of the radar system engineering and algorithm development group from 2002-2007, the deputy manager of the Climate, Oceans, and Solid Earth section from July 2007 to March 2009, and the section manager from April 2009 to Jan 2013. He served as the Project Scientist of the National Aeronautics and Space Administration (NASA) Aquarius mission from January 2012 to September 2013, the Deputy Project Scientist of NASA Soil Moisture Active Passive Mission from Jan 2013 to September 2013, and the SMAP Project Scientist since October 2013. He has been the Principal/Co-Investigator of numerous NASA and DOD research projects on remote sensing of ocean salinity, ocean wind, terrestrial snow, and soil moisture. He has authored four book chapters and published more than 300 publications and presentations. He received the 2021 IEEE J-STARS Prize Paper Award, the 2014 IEEE GRSS Transaction Prize Paper Award, the 2010 IEEE GRSS Transaction Prize Paper Award, the 2002 IEEE GRSS Transaction Prize Paper Award, the 2000 Best Paper Award in the IEEE International Geoscience and Remote Symposium 2000, and the 1995 IEEE GRSS Transaction Prize Paper award for a paper on polarimetric radiometry. He received the JPL Lew Allen Award in 1998, the Ed Stone Award in 2003 and 2023, the NASA Exceptional Technology Achievement Award in 2014, and the NASA Outstanding Public Leadership Medal in 2017. He was an associate editor of Radio Science from 2002 to 2006 and the Editor in Chief of IEEE Transactions on Geoscience and Remote Sensing from 2018-2022. He is a Fellow of IEEE and a member of URSI Commission-F.

Simon H. Yueh: [Email: | Project Scientist, Soil Moisture Active Passive Mission, Jet Propulsion Laboratory | Google Scholar | other]