Tuyuksu glacier as an indicator of change in the Zailiyskiy-Kungei Alatau glacial system during the last 60 years
Abstract:Glacial measurements in Zailiyskiy- Kungei Alatau mountainous systems (Tien Shan, Kazakhstan) began in the 1950s and proceeded in two ways: Detailed continuous mass balance and meteorological measurements were conducted at Tuyuksu (benchmark glacier of the WGMS) while wider inventories were conducted across the glacial systems using airborne and satellite measurements using Landsat 7 ETM+ imagery. At Tuyuksu, a valley glacier with a current map area of 2.27 km2, measurements started in 1957 and were conducted during the melt season becoming year-round in 1972. They include regular accumulation and ablation measurements from a network of 120 stakes, snow density and geodetic measurements and observations of temperature, precipitation, sun-shine hours and cloudiness at the meteorological station located at the foot of the glacier. Regional glacier inventories were conducted in 1955, 1974, 1979, 1990, 2008.
Analyses of the data of the inventories and mass balance observations are in good agreement and indicate that glaciers have been retreating since mid-1950s. Rates of retreat during different time periods changed from -0.65 to -1.38 % year-1. The average rate for the period 1956-2008 is 0.757 % year-1. Maximum rates observed for southern macro-slopes of the ridges.
The mass balance records from Tuyuksu indicate that cumulative mass balance has been declining since middle 1970s and annual mass balance was positive only 14 times for 58 years. Ablation season at Tuyuksu lasts between June and August while accumulation occurs around the year. There is a good correlation of the annual and winter mass balance. With the general increase of air temperature during the ablation period, in most cases the relatively small values of the summer balance correspond to previous winter balance.
The result of our research allow us to conclude that mass balance monitoring data of Tuyuksu glacier reliably reflect general trends in deglaciation of the Zailiyskiy- Kungei Alatau Mountains.