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Sensors 2008, 8(9), 5479-5491; doi:10.3390/s8095479

Impact of Soil Moisture Dynamics on ASAR σo Signatures and Its Spatial Variability Observed over the Tibetan Plateau

1
International Institute for Geo-Information Science and Earth Observation (ITC), Hengelosestraat 99, P.O. Box 6, 7500 AA Enschede, The Netherlands
2
Institute of Tibetan Plateau Research (ITP/CAS), P.O. Box 2871, Beijing 100085, P.R. China
*
Author to whom correspondence should be addressed.
Received: 30 June 2008 / Revised: 20 August 2008 / Accepted: 28 August 2008 / Published: 3 September 2008
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Abstract

This paper reports on the analysis of a 2.5 year-long time series of ASAR wide swath mode (WSM) observations for characterizing the soil moisture dynamics. The employed ASAR WSM data set consists of 152 VV-polarized scenes acquired in the period between April 2005 and September 2007 over the Naqu river basin located on the Tibetan Plateau. For four different spatial domains, with areas of 30x30 km2, 5x5 km2 and (two domains of) 1x1 km2, the mean backscatter (σo) and the standard deviation (stdev) have been computed for each ASAR acquisition. Comparison of the mean σo values with the stdev values results in a specific triangular distribution of data points for all spatial domains. Analysis of the mean σo and stdev with respect to in-situ soil moisture measurements demonstrates that this triangular shaped distribution can be explained by soil moisture dynamics during monsoon and winter periods. This shows that the relationship between the spatial mean soil moisture and variability is not uniquely defined and may change throughout seasons. Downscaling of coarse resolution soil moisture products should, therefore, be ideally based on additional near real time data sources. In this context, the presented results could form a basis for the development of SAR-based soil moisture downscaling methodologies. View Full-Text
Keywords: Soil moisture dynamics; ASAR; Time series; Tibetan Plateau Soil moisture dynamics; ASAR; Time series; Tibetan Plateau
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MDPI and ACS Style

Van der Velde, R.; Su, Z.; Ma, Y. Impact of Soil Moisture Dynamics on ASAR σo Signatures and Its Spatial Variability Observed over the Tibetan Plateau. Sensors 2008, 8, 5479-5491.

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