ИСТИНА

We present and discuss results of ground-based measurements and remote assessments of glacier albedo in the Ak Shyirak massif (Inner Tian Shan). Tendencies of decreasing albedo are typical for many glacierized mountain regions and lead to accelerating glacier downwasting. In the Ak-Shyirak massif the situation is complicated by technogenic dust pollution, whose contribution to albedo changes was unknown. Ground-based albedo measurements were carried out across 11 glaciers during summer and autumn in 2015-2018 using Sp Lite 2 Kipp&Zonen albedometer. Using ground albedo data from 2 glaciers and satellite imagery obtained on the same days, we developed models for ground correction of albedo values obtained from satellite data. A time series of images from Landsat and Sentinel 2 satellites for 1991-2018 were analysed to assess glacier albedo in the Ak Shyirak massif in different seasonal weather conditions. We compiled a series of albedo maps for the study area. In contrast to some other mountain regions we do not observe a decrease of glacier albedo in the Ak Shyirak massif since the 1990s. Glacier albedo in the Ak Shyirak massif is driven by natural environmental factors, mostly by elevation and preceding weather conditions. Technogenic impact (mechanical disturbance of glaciers within the Kumtor mine) is detected only locally, while technogenic dust on the background of natural dust is not traceable on glaciers with satellite imagery across the Ak-Shyirak massif.