Changes of polarimetric scattering characteristics of ALOS PALSAR caused by volcanic ash fall analyzed by the unsupervised wishart classifier

Full polarimetric SAR images of ALOS PALSAR of Shinmoedake volcano in Japan were analyzed. The volcano erupted in January, 2011 and volcano ash deposited more than 10 cm in 12 km² and 1 m in 2 km². Two images before and after the eruption were classified by the unsupervised classifier with the Wishart distance. The total numbers of classified classes of the two images are 11 and 17, respectively. The 11 classes of the image before the eruption can be coupled with the similar classes of the image after the eruption from a view point of the four-component scattering model. Changes of scattering characteristics to six new classes from a part of the 11 classes are clarified by interaction of the surface conditions and ash deposition to radio wave scattering.