PolSAR imaging of wetlands: New insights into backscatter physics

It is commonly-accepted that the enhanced backscatter from wetlands that consist of many emergent stems over open water (swamps and marshes) is dominated by double-bounce backscatter. Recent observations with fully polarimetric data from Radarsat-2 over the extensive wetlands of the Everglades and numerous small wetlands in Ontario are not consistent 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 has polarimetric characteristics normally attributed to the odd-bounce mechanism. A recently-proposed form of Bragg scattering provides a conceptual model to explain these observations. However, detailed electromagnetic backscatter modelling is still needed to provide a new and reliable understanding of backscattering from wetlands with emergent vegetation.