Широкополосное альбедо и изменения размера ледников массива АкШыйрак в период с 1994 по 2018 гг., Тянь-Шань, Кыргызстан

Abstract

The Ak-Shyjrak Massif is considered one of the main water sources of the Naryn (a tributary of the Syr Darya) and Sary-Dzhaz (a tributary of the Aksu and Tarim) Rivers and, thus, should be subject to annual surveying to forecast the water content of these rivers. This article examines the long-term dynamics of the broadband albedo of snow and ice, as well as the area dynamics of the Lysyi, Davydov and Sary-Tor South Glaciers of the Ak-Shyjrak Glacier Massif (Kyrgyzstan). The Landsat satellite data series were used as the source data. It was established that during 1994-2018 the retreat of the glacier tongue for the Lysyi amounted to 698 m, 381 m for the Sary-Tor South and 1,926 m for the Davydov. The total loss of glacier area came up to 1.7 km2 (39.6%) for the Lysyi, and 3.6 km2 (30.3%) cumulatively for the Sary-Tor South and Davydov. Since 2005, the melting has significantly slowed down compared to the previous years. Based on the shortwave and visible band data collected in 2006, the broadband albedo at the altitudes from 3,899 to 4,200 m ASL was extremely low compared to other satellite imagery. It was noted that in the accumulation zone – the altitude from 4,200 to 4,799 m – the snow cover was permanent leading to higher albedo values. In the course of 1994-2018, the mean broadband albedo had fluctuated from 0.200 to 0.531 (summer-autumn). A satellite image of 2006 with extremely low albedo values deserved special attention. The highest albedo value was recorded in 2018. The reason underlying the sharp albedo increase was the recent snowfall over the surveyed area.