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Title: Soil Moisture Retrieval Using a Two-Dimenional L-Band Synthetic Aperture Radiometer in a Semi-Arid Environment

Author
item RYU, D - University Of Melbourne
item Jackson, Thomas
item BINDLISH, R - Science Systems, Inc
item LE VINE, D - National Aeronautics And Space Administration (NASA)
item HAKEN, M - Science Systems, Inc

Submitted to: IEEE Transactions on Geoscience and Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2010
Publication Date: 12/1/2010
Citation: Ryu, D., Jackson, T.J., Bindlish, R., Le Vine, D., Haken, M. 2010. Soil moisture retrieval using a two-dimenional L-band synthetic aperture radiometer in a semi-arid environment. IEEE Transactions on Geoscience and Remote Sensing. 48:4273-4284.

Interpretive Summary: Microwave radiometry at L-band (~1.4 GHz) is the optimal solution for remote-sensing of soil moisture; however, satellite implementation has been limited by technological constraints on the size of large antennas required for the low-frequency radiometry. This limitation can be overcome by using interferometric aperture synthesis. The objective of this study was to contribute to a robust analysis of two-dimensional aperture synthesis for well characterized sites in Arizona and Sonora, Mexico. An aircraft prototype of this type of satellite radiometer called 2D-STAR was flown concurrent with intensive ground observations. The soil moisture retrievals from 2D-STAR indicate good performance of the L-band synthetic aperture microwave instrument over semi-arid region with diverse land surface conditions. The results of this study are very important to the future of spaceborne remote sensing and provide justification for the further development of this technology. The improved remote sensing capabilities of L-band interferometric radiometry will be of benefit to hydrologic applications in agriculture and climate

Technical Abstract: Surface soil moisture was retrieved from L-band radiometer data collected in semi-arid regions during the Soil Moisture Experiment in 2004 (SMEX04). The two-dimensional synthetic aperture radiometer (2D-STAR) was flown over regional-scale study sites located in Arizona, USA and Sonora, Mexico. The study sites are characterized by a range of topographic relief with land cover that varies from bare soil to grass and scrubland, and includes areas with high rock fraction near the soil surface. The 2D-STAR retrieval of soil moisture was in good agreement with the ground-based estimates of surface soil moisture in both Arizona (RMSE=0.012 m3m-3) and Sonora (RMSE=0.011 m3m-3). 2D-STAR also showed good performance in the Walnut Gulch Experimental Watershed (RMSE=0.014 m3m-3) where the surface soil featured high rock fraction was as high as 60%. Comparison of the results with the Polarimetric Scanning Radiometer (PSR) at C- and X-band data indicate the superior soil moisture retrieval performance of the L-band data over the regions with high rock fraction and moderate vegetation density.