祁连山七一冰川物质平衡的时空变化特征

基于2011-2016年七一冰川的野外观测资料,结合气象站数据及1975-2015年的遥感影像,分析了冰川末端变化、物质平衡时空变化特征及其对气候变化的敏感性,结果表明：1975年以来,七一冰川末端持续退缩235 m,平均退缩速率为5.9 m/a,冰川面积减少0.13 km²（4.5%）。2011-2016年,七一冰川的平均物质平衡为-476 mm w.e.,平均ELA为4941 m a.s.l.,物质平衡梯度为2.9 mm/m。从季节变化看,受风吹雪和冰面升华影响,11月至次年3月冰川呈负平衡;4月和9月物质平衡受降水控制,随海拔变化呈现降水效应;强消融期（6-8月）物质平衡随海拔升高线性增加;消融期末由9月初延后至9月底。敏感性分析结果表明,物质平衡对气温变化的敏感性为-178.7 mm w.e. °C^-1 a^-1,对降水变化的敏感性为+2.93 mm w.e. mm^-1 a^-1。即61 mm的降水增加才能弥补暖季气温升高1 °C引起的冰川净物质损失。

Spatial and temporal variations in mass balance of Qiyi Glacier in Qilian Mountains

Based on in-situ observations in Qiyi Glacier during 2011-2016, and combined with the data from meteorological stations and remote sensing images (1975-2015), this paper analyzed the glacier terminal change, spatial and temporal variations of glacier mass balance and its sensitivity to climate change. The results showed that: the terminal of Qiyi Glacier continued to retreat 235 m from 1975 to 2015, with a rate of 5.9 m/a, and the glacier area reduced by 0.13 km² (4.5%). During 2011-2016, the average annual mass balance of Qiyi Glacier was -476 mm w.e., the average ELA was 4941 m a.s.l., and the mass balance gradient was 2.9 mm/m. Affected by snowdrift and ice sublimation, the glacier mass balance tended to be more negative from November to March of the next year. Mass balance in April and September is dominated by precipitation, and the change with altitude showed the precipitation effect. Mass balance increased with altitude linearly from June to August, and the end of glacier melting season was delayed from early September to the end of September. The sensitivity analysis of glacier to climate change showed that, mass balance sensitivity to air temperature change was -178.7 mm w.e. ℃^-1 a^-1, while that to precipitation change was +2.93 mm w.e. mm^-1 a^-1. A 61 mm increase in precipitation was required to compensate for the net mass loss induced by an air temperature increase of 1 ℃.