Mass balance was measured on Tien Shan glaciers (Sary-Tor, Davydova (Photo 1), Tuyuksu and Glacier No. 1) since 1957. Shorter, 1-10 year measurements were carried out for couple of dozens of glaciers (http://instaar.colorado.edu/other/occ_papers.html and http://www.geo.unizh.ch/wgms/). The averaged over the longest observational period (1955-1995) mass balance values are ranged from -134 to -441 mm w.e./yr. The negative mass balance explains the overall retreat of Tien Shan glaciers in this period.
Central Asian glaciers were quasi-stable from the end of 1950’s to the beginning of 1970’s (Makarevich and Liu Chaohai, 1995). In the mid-1970’s the annual rate of glacier mass balance became more negative (Fig. 1). One of the possible reason of this shift to the new mode is the change in atmospheric pressures over the central North Atlantic Ocean during the mid-1970s. These changes promoted a decrease in atmospheric pressure and development of an anomalous flow of moist air from the North Atlantic Ocean into Europe and increased atmospheric pressures in Central Asia (McCabe et al., 2000). Intensification of anticyclone circulation over the Tien Shan has caused reducing of precipitation and total cloudiness. It is confirmed by an annual and summer air temperature and precipitation data at the meteorological station of “Tien Shan”, which is the highest in the region with long uninterrupted records from 1930 till now.
The specific values of annual glacier mass in Tien Shan decrease from west to east, i.e. in the same direction as the annual precipitation. These makes winter drier, snow pack thinner and ice temperature lower in the eastern part of the Tien Shan.
Photo 1. Sary-Tor Glacier, 2003. Photo by V.Mikhalenko
Fig. 1. Cumulative mass balance of the Tien Shan glaciers in mm w.e.
Dyurgerov, M.B., Kunakhovitch, M.G., Mikhalenko, V.N. et al., 1992. Can the mass balance of the entire glacier area of the Tien Shan be estimated? - Annals of Glaciology, Vol. 16, pp. 173-179.
Dyurgerov, M.B., Kunakhovitch, M.G., Mikhalenko, V.N. et al., 1992. Mass balance, runoff and meteorological conditions of Sary-Tor Glacier, Akshitrak Range (Interior Tian-Shan), 1985-1989. - Moscow , 69 pp. (in Russian with English summary)
Dyurgerov, M.B., Kunakhovitch, M.G., Mikhalenko, V.N. et al., 1993. Mass balance monitoring of the three Tien Shan glaciers. - Data of Glaciological Studies, Vol. 77, pp. 79-86 (in Russian with English summary)
Dyurgerov, M.B., Kunakhovitch, M.G., Mikhalenko, V.N. et al., 1995. Tien Shan Glaciers. Eds. by M. Dyurgerov and Xie Zichu, Moscow , Publishing House VINITI, 237 pp. (in Russian)
Dyurgerov, M.B., Mikhalenko, V.N., Kunakhovitch, M.G., et al., 1994. On the cause of glacier mass balance variations in the Tian Shan mountains. - GeoJournal, Vol. 33, No. 2/3, pp. 311-317.
Makarevich, K.G. and Liu Chaochai, 1995: Izmeneniya oledeneniya Tyan Shanya v 20 veke ( Tien Shan glaciation change in 20th century). In Dyurgerov, M., Liu Chaohai and Xie Zichu (eds.), Oledenenie Tyan Shanya (Tien-Shan Glaciers). Moscow : Publishing House VINITI, 189-213. (in Russian)
McCabe, G.J., Fountain, A.G. and Dyurgerov, M., 2000: Variability in winter mass balance of Northern Hemisphere glaciers and relations with atmospheric circulation. Arctic, Antarctic, and Alpine Research, 32(1): 64-72.
Mikhalenko, V.N., 1991. The peculiarities of mass exchange of the flat-top glaciers at the Central Tianshan (using the Grigoriev Glacier as an Example). - Journal of Glaciology and Geocryology, Vol. 13, No. 2, pp. 114-128.