The backscattering characteristics of thermokarst lake ice in the qinghai-tibet plateau from SAR

Abstract. A thermokarst lake is an important indicator of changes in climate, which cause considerable thermal distribution to the surrounding permafrost. The imaging radar has demonstrated the capability to determine when and which lakes freeze or do not freeze. In this paper, the temporal variability of C-band backscattering of thermokarst lakes at Beiluhe test area, is located on the central Qinghai- Tibet Plateau (QTP), were examined by 45 ENVISAT-ASAR imageries acquired in freeze up, ice duration and break-up stages. The SAR behaviour response for lake ice change are analysed with ASAR observation in experiments area. The results showed that the ice layer volume scattering and ice-water surface scattering were the two major scattering components in C-band VV polarization, which is also affected by the increase of bubble size, ice density and roughness of ice-water interface. According to this study, the timing of lake ice-on in fall and ice-off in spring for this geographic region can be identified in radar images by comparing radar backscatter from lake ice to its surrounding alpine meadow. When ice duration, the radar signature proved to be able to monitor the ice thickness over lake and deformation around the lake.