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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Hydrology and Remote Sensing Laboratory » Research » Publications at this Location » Publication #362872
Research Project: Integrating Remote Sensing, Measurements and Modeling for Multi-Scale Assessment of Water Availability, Use, and Quality in Agroecosystems

Location: Hydrology and Remote Sensing Laboratory

Title: Assessment and validation of AirMOSS P-band root zone soil moisture products

Author
item TABATABAEENEJAD, A. - University Of Southern California
item CHEN, R. - University Of Massachusetts
item BURGIN, M.S. - Jet Propulsion Laboratory
item DUAN, X. - Jet Propulsion Laboratory
item CUENCA, R. - University Of Oregon
item Cosh, Michael
item Scott, Russell - Russ
item MOGHADDAM, M. - University Of California

Submitted to: IEEE Transactions on Geoscience and Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2020
Publication Date: 3/18/2020
Citation: Tabatabaeenejad, A., Chen, R., Burgin, M., Duan, X., Cuenca, R., Cosh, M.H., Scott, R.L., Moghaddam, M. 2020. Assessment and validation of AirMOSS P-band root zone soil moisture products. IEEE Transactions on Geoscience and Remote Sensing. 58(9):6181-6196. https://doi.org/10.1109/TGRS.2020.2974976.
DOI: https://doi.org/10.1109/TGRS.2020.2974976

Interpretive Summary: The P-band portion of the microwave spectrum is sensitive to soil moisture at a soil depth not yet measured by satellites. An aircraft campaign was designed and conducted to map root zone soil moisture across several calibration and validation sites in the U.S. Over a three year period, measurements were made in coordination with ground networks which resulted in an calibrated data product within the expected accuracy for vadose zone remote sensing. Improvements could be achieved with better understanding of the land surface characteristics. Hydrologists and agriculturalists will benefit from future commercial products which could be developed using P-band technologies.

Technical Abstract: The Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) P-band synthetic aperture radar (SAR) was flown more than 1200 hours from August 2012 to September 2015, covering regions of 2500 km2 spread over nine major biomes in North America. The flights, as part of the NASA AirMOSS Earth Venture Suborbital 1 (EVS-1) mission, collected radar data used to map root-zone soil moisture (RZSM) at 3 arcsec resolution. We previously reported the baseline retrieval algorithm and demonstrated its performance for a semiarid shrubland (Walnut Gulch, AZ); we represented the RZSM profile as a continuous quadratic function and solved a radar scattering nonlinear optimization problem to obtain the unknown polynomial coefficients. In this paper, we expand the retrievals to other AirMOSS sites that in addition to the semiarid shrubland, include grassland and crops (MOISST, OK), woody savanna (Tonzi Ranch, CA), temperate conifer forest (Metolius, OR), and boreal forest (Saskatchewan, Canada). Due to a wide range of landcovers, soil types, and soil moisture regimes, we parameterize the forward model and constrain the inverse algorithm for each site separately. We present the full set of retrievals for these sites, validating the results against in-situ observations. Error sources and strategies to minimize their effects are discussed. The concept of sensing depth is introduced. We find that the retrieval errors are smallest for the top 25 cm of soil with a root-mean-squared-error (RMSE) of less than 0.05 m3/m3. The RMSE remains around 0.06 m3/m3 even for depths reaching 45 cm, which is the typical sensing depth for the sites considered. These AirMOSS RZSM products (known as Level 2/3 RZSM, or L2/3-RZSM, products) are the first of their kind in that it is the first time RZSM has been retrieved directly from remote-sensing observation.