1972-2017年南阿尔泰山中部冰湖变化特征及其对气候变化的响应

Characteristics of glacial lakes in the central part of the southern Altai Mountains from 1972 to 2017 and their responses to climate changes

以1972、1989、1996、2006、2017年5个不同时段的Landsat MSS/TM/ETM+/OLI遥感影像数据、数字高程模型(DEM)数据和气象数据为数据源,通过计算机自动提取与人工目视解译相结合的方法获取南阿尔泰山中部地区各时段的冰湖信息,利用GIS空间分析方法对该地区的冰湖面积进行统计,并分析研究区冰湖在不同规模、不同坡度、不同海拔状态下的时空变化特征。结果表明:①近45年来南阿尔泰山中部地区的冰湖面积呈“先减后增”趋势。1972-1996年研究区的冰湖面积从411.14 km^2减少至400.83 km^2,共减少了10.31 km^2,减少速率为0.43 km^2/a。从1996-2017年冰湖面积增加了15.42 km^2;增长率为0.514 km^2/a。②研究区冰湖分布主要集中在海拔低于2200 m、坡度小于25°的区域,不同海拔区间和不同坡度区间的冰湖面积均呈“先减后增”趋势。③结合气温、降水、冰川面积以及冰储量变化数据分析发现,南阿尔泰山中部地区冰湖对气候变化具有明显的响应。温度、降水量及冰川融水是影响冰湖面积变化的主要因素;且这三者之间存在一种平衡关系,即温度升高冰川消融速度加快,从而对冰湖的收支平衡产生直接影响。当冰湖的补给量(即冰川融水和降水量之和)大于由温度升高引起的蒸发量时,冰湖面积会呈增长趋势;反之亦然。1970-1980年整个阿勒泰地区年代际降水量减少了19.28 mm,温度上升了0.25℃,因此1972-1989年研究区冰湖的蒸发水量大于补给水量,导致该时段冰湖面积呈退缩态势。1989-1996年该区降水量增加了19.67%,温度升高了0.62℃,但是增加的降水量却无法弥补由温度升高引起的冰湖蒸发量,因此1989-1996年研究区冰湖面积仍处于退缩状态。1996-2017年由于温度和降水量大幅增加导致冰湖面积呈不断增长趋势。

This paper used the Landsat MSS/TM/ETM/OLI remote sensing image data,digital elevation model(DEM)data and meteorological data from five different periods in 1972,1989,1996,2006 and 2017 are used as data sources,and obtained the glacial lake information in the central part of South Altai Mountains by the method of automatic computer extraction and manual visual interpretation.This paper counted the area of glacial lakes in this area by GIS spatial analysis method,and analyzes the glacial lakes in different scales in the study area.The paper also analysed the slope,temporal and spatial variation characteristics at different elevations.The results show that:①In the past 45 years,the area of glacial lakes in the central part of South Altai Mountains showed the trend of"decreasing at first and then increasing".From 1972 to 1996,the area of glacial lakes in the study area decreased from 411.14 km 2 to 400.83 km^2,a total of 10.31 km^2 was reduced.The reduction rate of ice lake was 0.43 km^2/a.From 1996 to 2017,the area increased by 15.42 km^2;to 0.514 km^2/a.②The distribution of ice lakes in the study area is mainly concentrated in the area where the elevation is lower than 2200 m and the slope is smaller than 25°.The area of glacial lakes in different altitude range and different slope range shows the trend of"decreasing first and then increasing".②Combining with the analysis of temperature and precipitation data,we find that the change of glacial lake area in the central part of South Altai Mountains has obvious response to regional climate change.Temperature,precipitation and glacier melt water are the main factors affecting the change of glacial lake area.There is an equilibrium relationship among them,that is,the melting rate of glacier increases with the increase of temperature,which has an impact on the balance of revenue and expenditure of glacial lake.When the recharge amount of glacial lake(that is,the sum of glacier melt water and precipitation)is larger than the evaporation caused by rising temperature,the area of glacial lake will increase,and vice versa.The interdecadal precipitation of the whole Altay region decreased by 19.28mm from 1970 to 1980.The temperature increased by 0.25℃,which also led to the evaporation of glacial lake in the study area from 1972 to 1989,larger than that of recharge water,so the area of glacial lakes shrank during this period.From 1989 to 1996,the precipitation in this area increased by 19.67%,and the temperature increased by 0.62℃,but the increased precipitation cannot make up for the evaporation amount of glacial lake caused by the increase of temperature.Therefore,the area of glacial lakes in the study area from 1989 to 1996 is still in a state of retreat.From 1996 to 2017,the area of glacial lakes showed a growing trend due to the increase of temperature and precipitation.