Multi-temporal Analysis of ERS-1 and EMISAR C-band VV Backscattering Properties of Forest and Lake Surfaces in the NOPEX Region.

Multi-temporal ERS-1 SAR data, consisting of seven acquisitions in 1994 and 1995, were analyzed to determine the potential of C-band VV polarization backscattering data to discriminate different surface types within the patchy boreal landscape of the NOPEX area. Based on an aerial photo analysis, four classes of forest density were distinguished. For independent comparison, also one fully polarimetric EMISAR C-band image, including the VV polarization signatures was analyzed. It was found that the differences between the classes were quite consistent throughout the seasons and therefore probably significant, at least in a relative sense. The same images were also studied to determine the sensitivity of backscattering properties of lake surfaces to regional winds. For this purpose the backscattering values of five lakes within the study area were analyzed. It was found that the five lake surfaces behaved very similar, except for one observation date. This behavior, therefore, seems to be dominated by regional scale wind fields, although local scale wind fields also may have an effect. Since regional and local scale wind fields are difficult to observe in a synoptic way, the use of radar might have potential for monitoring such wind fields in the Swedish boreal region, which is characterized by the occurrence of many lakes.