1973-2010年青藏高原西部昂拉仁错流域气候、冰川变化与湖泊响应

采用距离昂拉仁错最近的狮泉河、改则和普兰地区1973-2010年的气象数据和覆盖昂拉仁错流域1973、1976、1990、2000、2001、2002和2009年共7a的Landsat卫星遥感影像提取湖泊变化信息,并选取1976、1990/1992、2001和2009年覆盖全流域的遥感影像分析流域内的冰川变化过程.分析过去近40a内昂拉仁错流域内气候、湖泊和冰川的变化,并探讨了不同时期引起昂拉仁错发生变化的原因.结果表明:昂拉仁错在过去近40a内出现先萎缩后扩张的变化趋势,2000年为转折年,整体的变化趋势为萎缩;流域内冰川在研究时段内一直处于萎缩状态,并持续补给昂拉仁错.分析比较流域附近3个站在气温、降水量和最大潜在蒸发量的变化趋势之后,选用与昂拉仁错流域气候变化最为相近的改则站的气象参数为参照分析引起昂拉仁错湖泊面积发生变化的原因.结果显示,昂拉仁错湖面变化的每个时期内,在气温持续升高、冰川持续消融补给昂拉仁错水量输入的背景环境下,蒸发量和降水量差值的变化主要调控了湖泊面积的变化;区域冰川量的减少与温度持续升高相匹配;当持续增加的冰雪融水与降水量对湖泊水量输入小于流域蒸发量时,湖泊面积萎缩;当冰川冻土随着温度进一步升高而加速融化、流域的降水量逐步上升;当二者的水量输入总和超过流域内蒸发量时,湖泊面积开始扩张.

Climate and Glacier Changes and Lake Response in the Ngangla Ringsto Catchment in Western Tibetan Plateau

In this paper,all the materials adapted are as follow: 1) meteorological data from three stations nearby Ngangla Ringsto,namely,Gaize,Shiquanhe and Pulan,from 1973 to 2010;2) Landsat remote sensing images covering the water area of Ngangla Ringsto in 1973,1976,1990,2000,2001,2002,and 2009,which were used to extract the information of lake changes,and images covering the whole catchment in 1976,1990/1992,2000 and 2009,which were used to gain the information of glacier changes in the drainage basin.On the base of above information,the changes in climate,lake and glacier during the past 40 years were analyzed,and the relationship between every factor that causes the lake area change of Ngangla Ringsto was preliminarily studied.It is fond that:(i) during the past 38 years,the lake area of Ngangla Ringsto decreased before 2000 and increased after that,with a general trend of increase;(ii)The glacierized area in the catchment has shrunk and consistently contributed the Ngangla Ringsto during that time span;(iii) After comparing the changing tendencies of temperature,annual precipitation and maximum of potential evaporation at the three meteorological stations,the data from Gaize Station is chosen as a reference to analyze the cause of the lake area change in Ngangla Ringsto.The result shows that in every changing stage it is a gap between the annual precipitation and maximum of potential evaporation in the catchment that controls the change in the lake area of Ngangla Ringsto.When the water input from precipitation and constantly increasing melt water is less than the amount of evaporation in the catchment,the lake area will decease,but when the water from the glacier melting and frozen soil thawing in a accelerated speed due to the rapidly rising temperature plus gradually increasing precipitation in the catchment finally surpasses the output from evaporation,the lake begins to expand.