Mass balance variation and associative climate drivers for the Dongkemadi Glacier in the central Tibetan Plateau

Glacier mass balance is a critical parameter in assessing glacial changes and meltwater runoff associated with climate change. This study used a modified distributed surface energy balance model at 3 hr temporal and 100- x 100-m spatial resolutions to reconstruct a 1960-2009 mass balance time series of the alpine Dongkemadi Glacier in the central region of the Tibetan Plateau. The modified distributed surface energy balance model was able to reasonably simulate glacier mass balance estimations. The average annual mass balance of the reconstructed long-term time series was -0.125 m w.e. (meter water equivalent), and the cumulative mass balance was -6.245 m w.e. throughout 1960-2009. Simulation results revealed that the glacier mass balance was more readily influenced by changes in air temperature (-362 mm w.e. [millimeter water equivalent]) than changes in precipitation (+138 mm w.e.). Therefore, a decreasing trend in the annual mass balance mainly derived from increasing air temperature throughout the simulated study period, although increasing precipitation inhibited the glacier ablation trend to some extent. Throughout 1960-2009, the glacial ablation zone expanded as shown by an increase in the equilibrium line altitude. This study offers comprehensive information on an important glacier monitored under harsh environmental conditions while aiding in our understanding of glacial response to climate change, using a method that can be applied to other glaciers to which mass balance observations are limited.