Glacier Surge-like signals detected by SAR-based technique in West Kunlun Shan, NW Tibet

High mountains at Tibetan plateau and Himalaya are the most glaciated area on the earth except for polar region. Mountain glaciers in High Asia are not only significant contributor to the global sea level rise, but also play an important role as water resource around the nearby densely populated regions. Severe nature and remote place, however, prevent us from operationally monitoring those mountain glaciers. Although a number of glacier have recently been studied using remote sensing techniques in these area, the surface velocity fields of the glaciers in High Asia still remains uncertain. Surge-type glaciers have been identified in certain regions, such as Alaska, Canada, Iceland, Pamirs and Karakoram. But there is no report in West Kunlun Shan (WKS), to our knowledge. We detected surface velocity fields and surge-like signal of mountain glaciers in WKS located in the north-west of Tibetan plateau, using offset tracking method based on Envisat/ASAR and ALOS/PALSAR data; average altitude of the WKS is greater than 4000m, and the highest peak (Liushi Shan) reaches 7167m. The temporal coverage of ASAR was from 2003 to 2007 and PALSAR was from 2007 to Feb. 2011, respectively. We converted the range and azimuth offset data to the surface velocity field, assuming that glaciers flow parallel to surface topography; the surface topography data were based on SRTM4 Digital Elevation Model. We detected a couple of anomalously fast flowing glaciers, comparing with the nearby valley glaciers. The most conspicuously moving glacier was the Unnamed Glacier located the northwest of WKS. While the other valley glaciers with similar elevation and scale flow at a rate of ~20 m/year, the Unnamed Glacier was 40 m/year from Sept. 2004 to Oct. 2004, and reached ~250 m/year from Dec. 2008 to Feb. 2009 at maximum. The SAR intensity image revealed an advance of the terminus by ~900m from Feb. 2009 to Feb. 2011.