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Title: Global soil moisture from the aquarius satellite: Description and initial assessment

item BINDLISH, R - Science Systems, Inc
item Jackson, Thomas
item Cosh, Michael
item ZHAO, T - Collaborator
item O'NEILL, PEGGY - National Aeronautics And Space Administration (NASA)

Submitted to: Geoscience and Remote Sensing Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2014
Publication Date: 5/1/2015
Publication URL:
Citation: Bindlish, R., Jackson, T.J., Cosh, M.H., Zhao, T., O'Neill, P.E. 2015. Global soil moisture from the aquarius satellite: Description and initial assessment. Geoscience and Remote Sensing Letters. 12:923-927.

Interpretive Summary: A global soil moisture product was developed by exploiting a NASA satellite (Aquarius) designed for ocean monitoring. Aquarius data were recalibrated for land applications and then a well-characterized soil moisture retrieval algorithm was adapted to the unique configuration of the instrument. Validation was performed using in situ observations at experimental watersheds and the assessment of global patterns. Results of these analyses indicated very good performance, which led to a decision by NASA to provide this as a standard product through its public distribution system. This research and the new product increases the value and impact of the Aquarius mission by including a broader scientific and applications community, particularly agricultural hydrology, and will contribute to a better understanding of the Earth’s climate and water cycle.

Technical Abstract: Aquarius satellite observations over land offer a new resource for measuring soil moisture from space. Although Aquarius was designed for ocean salinity mapping, our objective in this investigation is to exploit the large amount of land observations that Aquarius acquires and extend the mission scope to the retrieval of soil moisture. The first stage of our research focused on the use of the radiometer data because of the extensive heritage that this type of observations has in soil moisture applications. The Single Channel Algorithm (SCA) was implemented using the Aquarius observations to estimate surface soil moisture. Aquarius radiometer observations from the three beams (after bias/gain modification) along with the National Centers for Environmental Prediction (NCEP) model forecast surface temperature were then used to retrieve soil moisture. Ancillary data inputs required for using the SCA are vegetation water content, land surface temperature, and several soil and vegetation parameters derived based on land cover. The resulting global spatial patterns of soil moisture were consistent with the climatology and with the soil moisture from other satellite missions (Advanced Microwave Scanning Radiometer-E and SMOS). Initial assessments were performed using in situ observations from the Little Washita and Little River watershed soil moisture networks. Results showed good performance by the algorithm for these land surface conditions for the period of August 2011-June 2013 (RMSE=0.031 m3/m3, Bias=-0.007 m3/m3, and R=0.855). This radiometer-only soil moisture product will serve as a baseline for continuing research on both active and combined passive-active soil moisture algorithms. The products are now routinely available through the NASA data archives.