Arbindra Khadka, Fanny Brun, Patrick Wagnon, Dibas Shrestha, Tnzing Chogyal Sherpa

The sensitivity of glacier mass balance to temperature and precipitation variations is crucial for informing models that simulate glaciers’ response to climate change. In this study, we simulate the glacier-wide mass balance of Mera Glacier with a surface energy balance model, driven by in-situ meteorological data, from 2016 to 2020. The analysis of the share of the energy fluxes of the glacier shows the radiative fluxes account for almost all the energy available during the melt season (May to October). However, turbulent fluxes are significant outside the monsoon (June to September). On an annual scale, melt is the dominant mass flux at all elevations, but 44 % of the melt refreezes across the glacier. By reshuffling the available observations, we create 180 synthetic series of hourly meteorological forcings to force the model over a wide range of plausible climate conditions. A +1 (-1)°C change in temperature results in a -0.75 ± 0.17 (+0.93 ± 0.18) m w.e. change in glacier-wide mass balance and a +20 (-20)% change in precipitation results in a +0.52 ± 0.10 (-0.60 ± 0.11) m w.e. change. Our study highlights the need for physically based approaches to produce consistent forcing datasets, and calls for more meteorological and glaciological measurements in High Mountain Asia.