9 October 2006 On the comparison between soil moisture values retrieved from SAR images and ground truth point measurements
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Abstract
One major concern in the retrieval procedure lies in the procedure for its validation. This procedure implies a comparison between retrieved values and in-situ measurements. Even in the ideal case the ground and satellite measurements are fundamentally different, since the ground data can be sampled continuously in time but at a discrete point, while a satellite samples an area average but a snapshot in time. In this paper a retrieval algorithm for the estimation of soil moisture from AirSAR, acquired on vegetated fields during the SMEX'02 experiment carried out in Iowa in 2002, is presented. The retrieval procedure, based on a Bayesian approach, consists of two modules, one is pertinent to bare soils while the other one is useful for the determination of soil moisture in presence of vegetation. The last one uses the synergy with optical images to correct for the contribution of vegetation water content. The abovementioned campaign has been chosen because, along with radar observations, extensive ground truth measurements were acquired. The main aim of the paper is to investigate how well an average value of the ground variable, such as soil moisture, that is obtained by inverting the satellite data, corresponds to a simple average of the same variable over a finite region determined from ground truth data. This is what happens when satellite derived measurements are compared with point measurements.
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C. Notarnicola, F. Posa, "On the comparison between soil moisture values retrieved from SAR images and ground truth point measurements", Proc. SPIE 6363, SAR Image Analysis, Modeling, and Techniques VIII, 636308 (9 October 2006); doi: 10.1117/12.690696; https://doi.org/10.1117/12.690696
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