[A-CC26] Glaciology

[ACC26-P07] Glacier volume changes calculated by heat-balance glacier model over the high-mountain Asis

*Orie Sasaki¹, Koyori Ishikawa¹, Koji Fujita², Akiko Sakai², Shinjiro Kanae¹ (1.Tokyo Institute of Technology, 2.Nagoya University)

Keywords:glacier, heat balance-based glacier model, supraglacial debris, glacier runoff

Meltwater from snow and glaciers is an important source of freshwater over the high -mountain Asia. Especially in semi-arid regions such as Central Asia, glacier meltwater has a significant impact on streamflow during the dry season. On the other hand, a temporary increase of glacier runoff due to the global warming, combined with the projected increase in precipitation in Asia, will cause more severe water-related disasters in downstream areas. Therefore, how long the temporary increase in glacier meltwater will last and when it will start to decrease is important information for water policy in downstream areas. In order to determine the total amount of meltwater that flows into downstream areas on a basin scale, it is necessary to calculate the melting of all glaciers located within the basin. In the high-mountain Asia, it is necessary to simulate the melting of about 100,000 glaciers scattered throughout the region. Therefore, although several glacier models have been developed for wide-area calculations, there are still few models that can calculate the melting rate for each glacier in the world, and most of these models use an empirical method called the Positive Degree Day (PDD) method to calculate the glacier melt. The method has the advantage of requiring only a small number of climate values and low computational cost, and is suitable for wide-area calculations. However, it is reported that the PDD method would be sensitive to temperature rise under the future warming climate. In this study, we calculated the mass balance of individual glaciers based on the heat balance-based glacier model instead of the conventional PDD method. The use of the heat balance method also made it possible to take into account the effects of debris on glacier surface, which is known to affect the amount of glacier melting. The calculated results were validated with the observation data reported by the World Glacier Monitoring Service (WGMS) and Hugonnet et al. (2021). As a next step, we also aim to investigate the difference between our results and that of the PDD method, and discuss the range of uncertainty.