Energy and mass balance of Mera glacier (Everest region, Central Himalaya) and its sensitivity to climate

Recent glacier mass changes are very heterogeneous in High Mountain Asia, owing to climatic variability and the mass balance sensitivity to climate, which may differ from one region to another. Mera glacier in the Everest region is one of the longest field-based monitored and well-studied glaciers of the Central Himalaya. In this study, we examine the sensitivity of Mera glacier mass balance to climate variables using the COupled Snowpack and Ice surface energy and mass balance model in PYthon (COSIPY), using 4 years (2016-2020) of in-situ meteorological data recorded at different elevations in the ablation and accumulation zones of the glacier. This shows that the net short-wave radiation is the main energy input at the surface, and in turn albedo is a key parameter controlling the glacier mass balance. As a result, at 5360 m asl, in the ablation zone, surface melt accounts for 90% of mass loss whereas sublimation and subsurface melt account for less than 10%. This analysis is performed at point scale at 5360 and 5770 m asl, in the ablation and accumulation zones respectively, as well as in a distributed way. We produce and analyze 88 distinct climatic scenarios, varying from dry and warm to wet and cold conditions. Dry conditions, primary during the pre-monsoon and secondary during the monsoon, strongly decrease the glacier mass balance, revealing that the annual amount and the seasonal distribution of snowfalls primary drives the glacier-wide mass balance of Mera Glacier.