Re-establishing mass balance measurements on Aktru glaciers (Altai).

The rate of glaciers decline in the late 20th-early 21st centuries increased substantially. These circumstances are of particular relevance in mountainous areas, where glaciers are one of the most important landscape-forming factors, regulate river flow and serve as a potential source of hazardous processes and phenomena that threaten economic and recreational activities. The Aktru Glaciers (Maliy Aktru since 1962, Leviy Aktru and Vodopadniy since 1977) are the ‘reference’ glaciers of the World Glacier Monitoring Service (WGMS).

The Aktru glacier monitoring programs were suspended in 2012. There were only two glaciers with a continuous series of measurements in Russia. Both of these glaciers are located in the Caucasus. The vast area of Northern Eurasia at the current time is not covered with direct measurement data on glaciers, which does not allow to validate the results of global and regional projections of climate and environmental change and causes serious concern to the scientific community.

Here we present the first results of mass balance measurements on Leviy Aktru glacier re-established in 2019. The detailed accumulation measurements supplemented with new ablation stakes network and AWS enabled calculation of the mass balance of -425 mm w.e. in 2018/19. Ice thickness and bedrock topography was estimated using the GPR measurements. Additionally, the glacier volume changes from 2000 to 2019 were assessed for the region using SRTM-X and Pleiades DEM. The data obtained can be used to validate regional hydrological and mass balance models for Altai mountains.

The Pléiades stereo-pair used in this study was provided by the Pléiades Glacier Observatory initiative of the French Space Agency (CNES).