近20年乌鲁木齐河源1号冰川东支和西支物质平衡变化

Mass balance change in east and west branches of Glacier No. 1 at Urumqi riverhead,China,during last 20 years

利用乌鲁木齐河源1号冰川东支和西支1990/1991—2009/2010年的物质平衡资料,对比分析了东、西支的物质平衡变化。结果表明:东支的物质亏损量大于西支,平衡线高度(ELA)总体上低于西支,积累区比率(AAR)下降幅度大于西支;东支平均物质平衡-582 mm·a-1,累积物质平衡为-11638 mm,西支平均物质平衡-485 mm·a-1,累积物质平衡-9692 mm;东、西支平衡线高度均呈现升高趋势,分别升高了143、131 m;东、西支AAR下降了29.8%、19.6%。分析表明,物质平衡与ELA呈显著负相关,与AAR呈显著正相关,东、西支物质平衡减小100 mm,ELA分别升高19、23 m,AAR减小4.5%。物质平衡对气候变化的敏感性分析表明,当降水量不变时,夏季气温升高1℃,东支物质平衡减小487 mm,西支减小398 mm;当夏季气温不变时,降水量增加100 mm,东支物质平衡增大164mm,西支增大185 mm。在未来全球持续升温背景下,东、西支物质平衡将会继续减小。

Based on the mass balance data of east and west branches of Glacier No. 1 at Urumqi riverhead during 1990/1991-2009/2010, this paper analyzed the mass balance change in these branches. In the east branch, the amount of mass loss was greater than that in the west branch. The equilibrium line altitude （ELA） of the east branch was generally lower than that of the west branch, and the downward trend of accumulation area ratio （AAR） was greater in the east branch than in the west branch. During 1990/1991-2009/2010, the average mass balance and cumulative mass balance in the east branch were -582 mm·a-1 and -11638 ram, and those in the west branch were -485 mm ·a-1 and -9692 ram, respectively. The ELA of east and west branches showed a rising trend, with an increase of 143 m and 131 m, the AAR decreased by 29.8% and 19.6%, respectively. The mass balance was significantly negatively correlated with ELA, and significantly positively correlated with AAR. When the mass balance in east and west branches decreased by 100 ram, the ELA was decreased by 19 m and 23 m respectively, and the AAR decreased by 4.5 %. The sensitivity analysis of glacier mass balance response to climate change showed that when the precipitation unchanged, and if the summer temperature raised 1 ℃, mass balance in the east branch would be decreased by 487 mm, and that in the west branch would be decreased by 398 mm; when the summer temperature unchanged, and if precipitationincreased 100 mm, mass balance in the east branch would be increased by 164 ram, and that in the west branch would be increased by 185 mm. In the context of future global warming, mass balance in the east and west branches of Glacier No. 1 would be continued to decrease.