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TitlePolarimetric decompositions of temperate wetlands at C-band
AuthorBrisco, B; Ahem, F; Hong, S H; Wdowinski, S; Murnaghan, K; White, L; Atwood, D K
SourceRemote Sensing of Environment vol. 8, (2015), no. 7, 2015 p. 1-10,
Alt SeriesEarth Sciences Sector, Contribution Series 20150395
Mediapaper; on-line; digital
File formatpdf
NTS31F; 31G
AreaOttawa Valley
Lat/Long WENS -78.0000 -74.0000 46.0000 45.0000
Subjectsgeneral geology; mathematical and computational geology; miscellaneous; regional geology; surficial geology/geomorphology; radar probes; radar imagery; radar methods; vegetation; wetlands; water analyses; surface waters; SARS; electromagnetic mapping; computer mapping; Polarimetric radar; synthetic aperture radar; water resources
Illustrationslocation maps; Landsat images; tables; graphs; equations
ProgramLand Surface Characterization, Remote Sensing Science
AbstractC-band SAR is well established as a useful sensor for water resources applications. It is commonly accepted that the backscatter from wetlands that consist of many emergent stems over open water (swamps and marshes) is dominated by a doublebounce scattering mechanism. However, recent observations with fully polarimetric data from Radarsat-2 over the extensive wetlands of the Everglades and numerous small wetlands in Ontario appear to be inconsistent with this interpretation of the backscatter physics. In this paper, we use several forms of polarimetric analysis and decomposition. All of these indicate that the backscatter from small marshes and swamps in Ontario is dominated by polarimetric characteristics normally attributed to the oddbounce mechanism. This anomalous result might be explained as a consequence of changes in the double-bounce reflectance properties of vegetation as a function of the incidence angle. However, detailed electromagnetic backscatter modeling will be needed to provide a more complete and reliable understanding of the details of backscattering from wetlands with emergent vegetation. Additional observational and theoretical work will be required to document and understand the unusual results we report here. If these results are substantiated, the SAR community must re-interpret the generally accepted meanings of the popular decomposition variables, and introduce new terminology to describe them. This would lead to an improved understanding of the backscatter physics and better use of polarimetric SAR for wetland management applications.
Summary(Plain Language Summary, not published)
The objective was to explore how microwaves scatter in temperate mixed forest wetlands. A test site near Ottawa, ON which has been imaged extensively for SAR and water resource applications by RADARSAT-2 was used for this research. The Radarsat-2 polarimetric data for this study were acquired during 2011 on June 14, September 18, and November 5. The data were analysed for discrimnating seven land cover types, including two wetland classes, swamps and marshes. We also performed polarimetric decompositons and analysed the outputs as a function of these land cover types. The study illuminated an important issue in the understand of backscattering of wetlands that in many cases the enhanced backscatter of wetlands is NOT a result of double-bounce scattering but involves a more complex backscatter process. The data showed that these land cover classes could accuratley be classified indicating the RADARSAT Constellation Mission will be useful for wetland mapping and monitoring applications.