Glacier Surge in West Kunlun Shan, NW Tibet Detected by Synthetic Aperture Radar
Yasuda, Takatoshi; Furuya, Masato
Hokkaido University, JAPAN

West Kunlun Shan (WKS) is located to the northern-western Tibetan plateau. The annual precipitation is very low, but many glaciers are developed due to cold climate. Melt water are major water source around river and sustain people's life in arid region. Scientific researches of the glaciers have been very limited because of the remote location (Watanabe and Zheng 1987; Thompson et al. 1995).

Synthetic Aperture Radar (SAR) is one of the powerful tools to detect glacier surface dynamics (Rignot et al. 2011; Joughin et al. 2010). We used several SAR archive data from 1990's (ERS1-2, Envisat/ASAR, ALOS/PALSAR and TerraSAR-X) and detected surface velocity field in WKS based on offset tracking with parallel flow assumption. Offset tracking (feature tracking or intensity tracking) is a major method to detect surface displacements. Also we used archive data of Landsat optical image from 1970's to detect terminus position of glaciers in WKS.

Our results revealed surface velocity fields, including seasonal speed-up and glacier surge in WKS (Yasuda and Furuya 2013). We examined 36 glaciers in WKS. Among them, five glaciers (N2, West Kunlun, N7, Zhongfeng B1 and Chongce glacier) could be obviously identified as surge-type glacier. Surface velocity of these glaciers gradually accelerated and decelerated, accompanying the advance of glacier terminus. For examples, the N2 and West Kunlun have been surging since early 2000's. Peak velocity of N2 and West Kunlun reached ~255m/yr in late 2008 and ~210m/yr late 2009, respectively. These surge continued in 2012 and each velocity was ~150m/yr and ~350m/yr in 2012. Glacier terminus retreated from 1972 to 2007 and then advanced from late 2008. There was no surge signal before 2000. Other examples were Zhongfeng and Chongce glacier. These glaciers were decelerating in our observation period. The peak velocity of Zhongfeng and Chongce was ~1100m/yr in 2004 and ~800m/yr in 1996, respectively. These glaciers gradually were decelerated over several years and velocity profile changed significantly. The peak velocity degreased to ~30m/yr and the lower part of glacier became stagnant. This stagnant profile appeared some glaciers, such as West Yulong glacier and Yulong glacier. We could not detected velocity variation these glaciers but clearly terminus were advanced/retreated from 1976 to 2011.