Short communication:Extreme glacier mass loss triggered by high temperature and drought during hydrological year 2022/2023 in Qilian Mountains

In the hydrological year 2022/2023,the glaciers in the Qilian Mountains experienced unprecedented mass loss.The glacier-wide mass balance was-1,188 mm w.e.,in contrast to-350 mm of average mass balance since 1990 over the Bailanghe Glacier No.12 in the middle of Qilian Mountains.The temperature during 2022–2023 reached the highest value ever recorded,second only to 2022,while at the same time the precipitation amount was less compared to other year since 2000,which together led to the strongest glacier mass loss during 2022–2023.The atmospheric circulation analysis shows that the high temperature in the Qilian Mountains in 2023 was jointly caused by the Arctic air mass and East Asian monsoon.

The mass-balance characteristics and sensitivities to climate variables of Laohugou Glacier No.12,western Qilian Mountains,China

Due to global warming, glaciers on the Tibetan Plateau(TP) are experiencing widespread shrinkage; however, the mechanisms controlling glacier variations across the TP are still rather unclear, especially on the northeastern TP. In this study, a physically based, distributed surface-energy and mass-balance model was used to simulate glacier mass balance forced by meteorological data. The model was applied to Laohugou No. 12 Glacier, western Qilian Mountains, China, during2010~2012. The simulated albedo and mass balance were validated and calibrated by in situ measurements. The simulated annual glacier-wide mass balances were-385 mm water equivalent(w.e.) in 2010/2011 and-232 mm w.e. in 2011/2012,respectively. The mean equilibrium-line altitude(ELA) was 5,015 m a.s.l., during 2010~2012, which ascended by 215 m compared to that in the 1970 s. The mean accumulation area ratio(AAR) was 39% during the two years. Climatic-sensitivity experiments indicated that the change of glacier mass balance resulting from a 1.5 °C increase in air temperature could be offset by a 30% increase in annual precipitation. The glacier mass balance varied linearly with precipitation, at a rate of130 mm w.e. per 10% change in total precipitation.

Potential Effect of Black Carbon on Glacier Mass Balance during the Past 55 Years of Laohugou Glacier No. 12, Western Qilian Mountains

This study reconstructed the annual mass balance(MB)of Laohugou Glacier No.12 in the western Qilian Mountains during 1961–2015.The annual MB was calculated based on a temperature-index and an accumulation model with inputs of daily air temperature and precipitation recorded by surrounding meteorological stations.The model was calibrated by in-situ MB measurements conducted on the glacier during 2010–2015.Change in constructed annual MB had three phases.During Phase Ⅰ(1961-1984),glacier-wide MB values were slightly positive with an average MB of 24±276 mm w.e.(water equivalent).During Phase Ⅱ(1984-1995),the MB values became slightly negative with an average MB of?50±276 mm w.e..The most negative MB values were found during Phase Ⅲ(1996–2015),with an average MB of?377±276 mm w.e.Climatic analysis showed that the warming led to accelerated glacier mass loss despite a persistent increase of precipitation during the analysis period.However,an increase of black carbon deposited on the glacier surface since the 1980s could have contributed to intensified glacier melt.From simulations and measurements of MB on the Urumqi Glacier No.1,26%of glacier melt caused by black carbon could be identified.