The Influence of Key Climate Variables on Mass Balance of Naimona'nyi Glacier on a North-Facing Slope in the Western Himalayas

摘要

Glacier mass changes in the Himalayas impact on sustainable water resources and hazards in downstream regions. However, mass balance variation and its drivers on north-facing slopes in the Himalayas are not well understood. This study presents the meteorological conditions, energy and mass balance characteristics for Naimona'nyi Glacier on a north-facing slope in the western Himalayas, based on energy-mass balance model and high-altitude measurements from October 2010 to September 2018. The average annual mass balance measured for Naimona'nyi Glacier was -0.39 m water equivalent a~(-1) and point mass balances below 6,070 m above sea level were always negative. Simulations showed that melt during the ablation season dominated the annual mass balance and the interannual variability in the mass balance, and that variability in melt energy was controlled by albedo during the ablation season. The annual mass balance was found to be significantly correlated with annual precipitation during the 2011-2018 period, which is accounted for by the change in ablation-season albedo and melt energy. The average mass balance for glaciers in the western Himalayas were higher during the 2010-2019 period than during the 2000-2009 period, partly because of higher annual precipitation during the 2010-2019 period. Over the last 20 years, the increased precipitation in the cold season was driven by a cyclonic circulation anomaly over the northwestern Indian Peninsula, which may be linked to the strengthened North Atlantic Oscillation, and the increased precipitation in the ablation season was driven by an anomaly in the cyclonic circulation over Central India, which may be related to enhanced deep convection over the Indian subcontinent and the enhanced Atlantic multidecadal oscillation.