Thickness and Volume of Glaciers of the Mongun-taiga Massif, Altai, in 2021 Based on Ground Penetrating Radar Data and Modeling

Abstract

Received April 26, 2023; revised August 18, 2023; accepted October 2, 2023This article presents the results of estimating the scale of the present-day glaciation of the Mongun-Taiga Mountain range (Eastern Altai) based on the decoding multi-time satellite images, GPR data and modelling using GlabTop2 and the Volume-Area Scaling (VAS) method. By 2021, 38 glaciers have been identified according to the hydrological principle and 36 ones – by the morphological principle. The total area is estimated as 17.18 ± 1.13 km2. Since 2010, area of the glaciers has decreased by 15%. The thickness of the glacial complex on the main peak of the Mongun-Taiga Mountain range was measured in the ablation season of 2021. More than 6 km of profiles were obtained by the GPR survey with accuracy of about 1%. Based on these data, the GlabTop2 model was calibrated. Then the spatial distribution of the ice thickness was obtained over the entire massif. The total volume of ice in the flat-summit glacier № 17 is estimated at 0.202 ± 0.008 km3 of ice. According to the GlabTop2 model with the morphological approach the ice volume of the whole massif was estimated at 0.733 ± 0.052 km3, and with the hydrological approach: 0.888 ± 0.061 km3. Determination of the boundaries of glaciers by the VAS method gave larger values: 0.690 ± 0.038 km3 with a morphological approach and 0.757 ± 0.036 km3 with a hydrological method. Consequently, with the same area of glaciers, volume determined by two different approaches can be rather different. This has a decisive influence on the morphological structure of ice reserves: the role of large forms of glaciation sharply prevails with the morphological approach. Most of the ice is contained in glaciers of the flat summit (27–40%). With the hydrological approach, which is used most often, the role of small forms of glaciation is overestimated. At the same time, the contribution of flat-summit glaciers is estimated at only 2%.