Appropriate scale of soil moisture retrieval from high resolution radar imagery for bare and minimally vegetated soils

被引：46

作者：

Thoma, D. P. ^{[1
]}

Moran, M. S. ^{[1
]}

Bryant, R. ^{[1
]}

Rahman, M. M. ^{[2
]}

Collins, C. D. Holifield ^{[1
]}

Keefer, T. O. ^{[1
]}

Noriega, R.

Osman, I. ^{[3
]}

Skrivin, S. M. ^{[1
]}

Tischler, M. A. ^{[4
]}

Bosch, D. D. ^{[5
]}

Starks, P. J. ^{[6
]}

Peters-Lidard, C. D. ^{[7
]}

机构：

[1] USDA ARS, SW Watershed Res Ctr, Tucson, AZ 85719 USA

[2] Saskatchewan Environm Planning & Risk Analysis Di, Regina, SK, Canada

[3] Univ Arizona, Tucson, AZ 85721 USA

[4] USA, Corps Eng Topog Engn Ctr, Alexandria, VA USA

[5] USDA ARS, SE Watershed Res Ctr, Tifton, GA 31793 USA

[6] USDA ARS, Nat Resources Res Unit, El Reno, OK USA

[7] NASA, Goddard Space Flight Ctr, Hydrol Sci Branch Code 6143, Greenbelt, MD USA

来源：

REMOTE SENSING OF ENVIRONMENT | 2008年 / 112卷 / 02期

关键词：

radar; soil moisture; scale;

D O I：

10.1016/j.rse.2007.06.021

中图分类号：

X [环境科学、安全科学];

学科分类号：

08 ; 0830 ;

摘要：

This research investigates the appropriate scale for watershed averaged and site specific soil moisture retrieval from high resolution radar imagery. The first approach involved filtering backscatter for input to a retrieval model that was compared against field measures of soil moisture. The second approach involved spatially averaging raw and filtered imagery in an image-based statistical technique to determine the best scale for site-specific soil moisture retrieval. Field soil moisture was measured at 1225 m(2) sites in three watersheds commensurate with 7 m resolution Radarsat image acquisition. Analysis of speckle reducing block median filters indicated that 5 x 5 filter level was the optimum for watershed averaged estimates of soil moisture. However, median filtering alone did not provide acceptable accuracy for soil moisture retrieval on a site-specific basis. Therefore, spatial averaging of unfiltered and median filtered power values was used to generate backscatter estimates with known confidence for soil moisture retrieval. This combined approach of filtering and averaging was demonstrated at watersheds located in Arizona (AZ), Oklahoma (OK) and Georgia (GA). The optimum ground resolution for AZ, OK and GA study areas was 162 m, 310 m, and 1131 m respectively obtained with unfiltered imagery. This statistical approach does not rely on ground verification of soil moisture for validation and only requires a satellite image and average roughness parameters of the site. When applied at other locations, the resulting optimum ground resolution will depend on the spatial distribution of land surface features that affect radar backscatter. This work offers insight into the accuracy of soil moisture retrieval, and an operational approach to determine the optimal spatial resolution for the required application accuracy. Published by Elsevier Inc.

引用

页码：403 / 414

页数：12

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