Coastal wetland monitoring using multi-frequency polarimetric SAR
Sang-Eun Park(1), Wooil M. MOON(2), Duk-jin KIM(3) and Eric POTTIER(1)
(1) University of Rennes 1, IETR, Bat 11D, 263 Avenue General Leclerc, 35042 RENNES, France
(2) University of Manitoba, Satellite Geophysics, Winnipeg MB R3T 2N2, Canada
(3) Seoul National University, Gwanak-gu, silrim-dong, Seoul 151-747, Korea
Coastal wetlands are highly productive and have dynamic and diverse ecosystems. Korea's well developed coastal wetlands including tidal flats occur along the west and south coasts. Despite the importance of the tidal flats and associated coastal habitats, theses areas are at risk due to high development pressure, such as reclamation and marine pollution. In addition, coastal wetlands are highly vulnerable to climate changes. Microwave remote sensing using synthetic aperture radar (SAR) system has great potential for quantitative monitoring and mapping of coastal wetlands. There are now fully polarimetric space-borne SAR systems in three frequencies, X-, C-, and L-bands available for us to use, which will be an extremely valuable research tools for monitoring wetlands. In this study, multi-frequency polarimetric air-borne and space-borne SAR measurements have been used to extract information on the surface characteristics in and around the Suncheon Bay in the southern coast and Kyunggi Bay in the western coast of the Korean peninsular. The L- and P-band NASA/JPL AIRSAR and L-band ALOS PALSAR data sets have been acquired over study areas at Quad- and Dual-Pol modes. SAR polarimetry with polarimetric decomposition technique allows discrimination of different types of scattering mechanisms. This study aims to demonstrate its capacity for the assessment of natural habitats especially coastal wetlands. Particularly, multi-frequency polarimetric target characterization methods are presented in this study for extracting information on features of vegetation in coastal wetlands. In addition, polarimetric forward/inverse scattering models have been developed for quantitative estimation of geophysical parameters such as soil moisture and surface roughness. Roughness inversion algorithms proposed in this paper are useful to estimate the biogenic and physical roughness structures of intertidal flats in coastal wetlands. Recent changes in costal wetlands will be continually monitored using C-band RADARSAT-2 and X-band TerraSAR-X as well as the PALSAR data sets.