A sequential model for disaggregating near-surface soil moisture observations using multi-resolution thermal sensors

Abstract : A sequential model is developed to disaggregate microwave-derived soil moisture from 40 km to 4 km resolution using MODIS (Moderate Imaging Spectroradiometer) data and subsequently from 4 km to 500 m resolution using ASTER (Advanced Scanning Thermal Emission and Reflection Radiometer) data. The 1 km resolution airborne data collected during the three-week National Airborne Field Experiment 2006 (NAFE'06) are used to simulate the 40 km pixels, and a thermal-based disaggregation algorithm is applied using 1 km resolution MODIS and 100 m resolution ASTER data. The downscaled soil moisture data are subsequently evaluated using a combination of airborne and in situ soil moisture measurements. A key step in the procedure is to identify an optimal downscaling resolution in terms of disaggregation accuracy and sub-pixel soil moisture variability. Very consistent optimal downscaling resolutions are obtained for MODIS aboard Terra, MODIS aboard Aqua and ASTER, which are 4 to 5 times the thermal sensor resolution. The root mean square error between the 500 m resolution sequentially disaggregated and ground-measured soil moisture is 0.^062 vol./vol. with a bias of −0.045^ vol./vol. and values ranging from 0.08 to 0.40^ vol./vol.
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Remote Sensing of Environment, Elsevier, 2009, pp.RSE-07453; No of Pages 10. 〈10.1016/j.rse.2009.06.012〉
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O. Merlin, A. Al Bitar, J P. Walker, Y.H. Kerr. A sequential model for disaggregating near-surface soil moisture observations using multi-resolution thermal sensors. Remote Sensing of Environment, Elsevier, 2009, pp.RSE-07453; No of Pages 10. 〈10.1016/j.rse.2009.06.012〉. 〈ird-00403130〉

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