Interpretation of radarsat SAR scenes of Sagwon Alaska, to establish temporal, spatial and physical active layer behavior

Abstract

Radarsat SAR images of the Kuparuk Basin in North Alaska can be used to describe the timing and characteristics of the seasonal freeze-thaw cycle and the spatial distribution of two types of Arctic Tundra. The freezing of the ground surface; decreases backscatter brightness by 3dB allowing the date of freeze-up and thaw to be established. Using Empirical Orthogonal Functions on amplitude images allows the subtle change in the brightness (during winter) of different tundra types to be enhanced, which provides a technique for discriminating between areas of Moist Acidic Tundra and Moist Non-acidic Tundra. The sand to clay ratio affects the backscatter properties of frozen soil and is inferred to cause this brightness difference. Coherence images show the dynamic nature of Arctic tundra, and low coherence limits the applicability of interferometric techniques to describe active layer heave, however, preliminary results show promise in the application of a differential interferometric technique.