Comparison of ranging scatterometer and ERS-1 SAR microwave signatures over boreal forest zone during winter season

A set of ERS-1 SAR images along with airborne non-imaging ranging scatterometer (HUTSCAT) measurements and in-situ surveys has been obtained from the Sodankyla test site in Northern Finland. A total of 5 measurement campaigns have been organized during the years 1991 to 1993. 19 test lines have been selected from the test site to represent different land-use classes. Microwave signatures representing the test lines have been extracted from ERS-1 SAR images and HUTSCAT measurements. The behaviour of these signatures has been compared to each other and with boreal forest semi-empirical backscattering model. The results indicate that the behaviour of ERS-1 SAR derived microwave signatures are similar to those of HUTSCAT even in the presence of forest canopies. By using the semi-empirical model the ERS backscattering is divided into two contributions 1) contribution from top of the canopy and 2) contribution from ground, trunks and ground-canopy reflections. This can be used for analyzing forest backscattering mechanism under various conditions