Abstract
Energy exchanges between atmosphere and glacier surface control the net energy available for snow and ice melt. Based on the meteorological records in Urumqi River Glacier No.1 (URGN1) in the Chinese Tien Shan during the period of 2012–2015, an energy-mass balance model was run to assess the sensitivity of glacier mass balance to air temperature (T), precipitation (P), incoming shortwave radiation (Sin), relative humidity (RH), and wind speed (u) in the URGN1, respectively. The results showed that the glacier melting was mainly controlled by the net shortwave radiation. The glacier mass balance was very sensitivity to albedo for snow and the time scale determining how long the snow albedo approaches the albedo for firn after a snowfall. The net annual mass balance of URGN1 was decreased by 0.44 m w.e. when increased by 1 K in air temperature, while it was increased 0.30 m w.e. when decreased by 1 K. The net total mass balance increased by 0.55 m w.e. when increased precipitation by 10%, while it was decreased by 0.61 m w.e. when decreased precipitation by 10%. We also found that the change in glacier mass balance was non-linear when increased or decreased input condition of climate change. The sensitivity of mass balance to increase in Sin, u, and RH were at −0.015 m w.e.%−1, −0.020 m w.e.%−1, and −0.018 m w.e.%−1, respectively, while they were at 0.012 m w.e.%−1, 0.027 m w.e.%−1, and 0.017 m w.e.%−1 when decreasing in those conditions, respectively. In addition, the simulations of coupled perturbation for temperature and precipitation indicated that the precipitation needed to increase by 23% could justly compensate to the additional mass loss due to increase by 1 K in air temperature. We also found that the sensitivities of glacier mass balance in response to climate change were different in different mountain ranges, which were mainly resulted from the discrepancies in the ratio of snowfall to precipitation during the ablation season, the amount of melt energy during the ablation season, and precipitation seasonality in the different local regions.
Highlights
Glacier play a crucial role in streamflow regimes in the arid regions of Central Asian, especially during the summer with little precipitation, as meltwater from the glacier is released when other sources are depleted[1,2,3]
Based on the records in automatic weather station 2 (AWS2), we found that the mean annual air temperature was −4.97 °C, and there was a significantly increased trend of 0.25 °C/decade (p < 0.0001) from 1958 to 2015 (Fig. 2)
We found that arithmetic mean of S↓ was at 173.57 W/m2 and ranged from 0 W/ m2 to 1284 W/m2, arithmetic mean of S↑ was at 57.68 W/m2 and ranged from 0 W/m2 to 874 W/m2, arithmetic mean of L↓ was at 232.58 W/m2 and ranged from 125.97 W/m2 to 375.97 W/m2, and arithmetic mean of L↑ was at 303.34 W/m2 and ranged from 192.17 W/m2 to 583.40 W/m2
Summary
Glacier play a crucial role in streamflow regimes in the arid regions of Central Asian, especially during the summer with little precipitation, as meltwater from the glacier is released when other sources (e.g. precipitation and snowmelt) are depleted[1,2,3]. The environment of glacierized regions and glacier-melt patterns were changed with global warming, such as the changes in air temperature, precipitation, and their contribution to glacial runoff. The models can compute the component of mass balance from each relevant energy fluxes at the glacier surface, which is important to understand the interaction between glacier melt and climate change. To assess the performance of the models with different melt regimes, an experiment was conducted by running the five different melt models[32], including the classical Temperature-Index model, Temperature-Index model of Hock[15], an Enhanced Temperature-Index model, a simplified Energy-Balance Model, and an Energy-Balance Model. Local environment and glacier melt pattern were changed due to climate change and glacier retreat
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