纳木错流域冰川和湖泊变化对气候变化的响应

Glaciers and Lake Change in Response to Climate Change in the Nam Co Basin,Tibet

利用纳木错流域及其周边地区气象资料、地形图、遥感资料以及野外实地观测资料,对该流域过去37年来气候变化特征以及冰川、湖泊变化过程进行了分析。结果表明,自1970年以来,纳木错区域气温上升趋势明显,其中冬季升温幅度高于夏季;降水量变化冬、夏两季均呈增加趋势,但冬季增加量不显著。在整体升温的背景下,纳木错流域冰川整体呈退缩趋势。1970～2007年间,流域内冰川面积减少37.1km2,占流域冰川面积的18.2%,年变化率为-1.0km2/a。流域内扎当冰川和拉弄冰川末端GPS观测表明,1970～2008年间冰川末端分别退缩381.8m和489.5m,年均退缩量为10.3m和13.4m。1970～2007年间,纳木错湖面积增加了72.6km2,增加速率为2.0km2/a。1970～1991年、1991～2000年和2000～2007年三个阶段的年增加速率不断增大,分别为1.1、2.8、3.4km2/a;湖泊水位在夏季升高非常显著,与湖泊面积的扩张是一致的。

Meteorological data, topographic maps, remotely sensed data and field observation data of the Nam Co Basin were used to analyze the characteristics of climate change, glacier and lake variations during the past 37 years. The results showed that the annual temperature rose distinctly while the annual precipitation had an indistinctive increase for the basin since 1970. The magnitude of warming in winter was much higher than in summer. Affected by the climate warming, the glaciers in the Nam Co Basin were undergoing an overall shrinkage. During the 1970 to 2007, the glacier area reduced 37. 1 km^2 accounted for 18.2 % of the whole glacier area in the Nam Co Basin. The annual glacier change ratio is - 1.0 km^2/a. The GPS surveying results showed that the terminals of Zhandang glacier and Lanong glacier had retreated 381.8 m and 489.5 m with the annual change ratio of 10. 3 m/a and 13. g m/a respectively. At the same time, the area of the Nam Co Lake increased 72. 6 km2 with an annual increase rate of 2.0 km^2/a During the three period 1970 - 1991,1991 - 2000 and 2000 - 2007, the annual increase rate has been growing. The water level of the Nam Co Lake has a notable increase in summer season which is coincident with the expanding of lake area.