Change detection on Alaska´s North Slope using repeat-pass ERS-1 SAR images

Measurements of the C-band (wavelength=5 cm) radar cross section of an area in the Brooks Range foothills on the North Slope of Alaska using images from the ERS-1 satellite that show significant temporal changes occur. These changes are strongly correlated with elevation and hill-slope orientation and are greatest on some of the elevated areas and weaker in river drainages. By constructing difference images using various image pairs, and by analyzing climatological and hydrological data from the site, it is concluded that the radar backscatter changes are largely due to changes in soil and vegetation liquid water content induced by freeze/thaw events. The correlation with topography in the difference images arises from the dependence of vegetation, organic layer thickness, and volumetric water content on hill-slope position and orientation. These results demonstrate the viability of radar backscatter intensity comparisons using repeat-pass images as a means of change detection