Glacier Snow Line Detection on a Polarimetric SAR Image

Synthetic aperture radar (SAR) can be used to distinguish areas of contrasting backscatter on glaciers and relate these areas to glacier facies. In the ablation season, there are two typical facies on temperate mountain glaciers: wet snow and ice. The boundary of wet snow and ice is defined as the transient snow line (TSL), which is an important concept in glaciology. In this letter, a new TSL detection method is proposed, in which the polarimetric SAR image is classified into three classes (wet snow, ice, and others) using support vector machines, and the boundary between wet snow and ice on the classification map is considered the TSL. The method is efficient and accurate and enables large-scale TSL observation. In our work, the TSL is extracted and analyzed on the long-observed Dongkemadi glacier using the proposed method. In addition, the method is applied on other neighboring glaciers to estimate their snow line altitude. On a regional scale, the TSL of the glacier group shows interesting phenomenon in the study area: The TSL altitude correlates closely with the orientation of the glaciers.