Сравнительная динамика отдельных ледников массива Мунку-Сардык (Восточный Саян) и хребта Цаст-Ула (Монгольский Алтай)

Abstract

Continuing the study of modern glaciation on the example of individual mountain ranges of the inland part of Asia along the latitudinal transect from the Kodar Mountains to the Himalayas, this work considers the Tzast-Ula massif in the Mongolian Altai. These glaciers, as objects of the transect, represent its western part. The glaciers of northwestern Mongolia are studied by glaciologists, although not as detailed as the glaciers of the central part of Altai and the Tien Shan. It is interesting to consider their dynamics in comparison with other glacial massifs of the transect. In the Eastern Sayan, the most studied (more than 100 years) are the nival-glacial objects of the Munku-Sardyk range. In this paper, changes in glaciers at the main peaks of the Munku-Sardyk mountain range and the Tzast-Ula ridge are considered. Throughout the transect there is a reduction in glaciers and an increase in the intensity of armor by surface moraines. Moraine reservation of the lower part of the small glaciers of Tzast-Ula occurs, similar to the glaciers of Munku-Sardyk. According to the remote sensing data (Landsat), a comparison of the dynamics of both the entire massif and individual glaciers No. 7, 8 Tzast-Ula and glaciers No. 31 (Peretolchina) and No. 30 (Radde) was made, which shows that glaciers are shrinking to varying degrees. Since the mid-1970s, Glacier No. 7 has shrunk in area by 19 %, in length by about 5 %, No. 8 by 58 % and 31 %, respectively. The decrease in the area of the entire Tsambaragav massif on average took place at a speed of 0.31 km2/year. The glaciers of Tzast-Ula were shrinking unevenly at an average speed of 0.32 km2/year, losing 22 % of their area. The glaciers of the Munku-Sardyk massif are shrinking about 4 times slower. Over the past 20 years, the Peretolchina glacier has been shrinking in area at a rate of 0.005 km2/year, and for the entire observation period since 1900—0.004 km2/year. In length, during the same period, the glacier was shrinking at a rate of 5 m/year. The open part of the Peretolchina glacier from the final moraine of the end stage of the Little Ice Age decreased both in area and length by about half. Anomalous changes were detected in the glaciers under consideration in 2013–2015, both for the Tzast-Ula ridge and for Munku-Sardyk. By 2013–2014, there was an increase in the area of the open part of glaciers and the area of perennial snowfields and a sharp decrease after 2015, in some cases in the form of a descent of parts of glaciers.