天山北坡典型内陆河流域积雪年内分配与年际变化研究——以玛纳斯河流域为例

Snow cover change in Manasi River Basin during 2007 and 2008,1960 and 2006

以500m分辨率的MOD10A2积雪遥感影像和气象站点数据为基础,以积雪覆盖率和初雪日与积雪日数为变量对玛纳斯河流域积雪的年内分配(2007年10月-2008年9月)与年际变化(1960年-2006年)进行了分析探讨。结果表明:水文年内玛纳斯河流域积雪变化较大,北部开阔的河谷地带积雪覆盖呈现明显的季节性变化;南部山区海拔较高,季节性积雪消融后,流域冰川主要分布在海拔3600m以上的山顶以及山谷间西北向的坡地上。同时,1960～2006年间玛纳斯河流域积雪呈现出初雪日推迟和积雪日数减短的趋势。对流域初雪日出现的频率分析表明:1960～1988年间流域初雪日出现的时间相对较早,平均出现日期为每年的第303天,1994-2006年间初雪日有显著推迟,平均出现日期为每年的第313天。于此同时,玛纳斯河流域的积雪日数呈减少趋势,速度为0.06天/年,该速度小于初雪日推迟的速度0.3天/年,这说明初雪日推迟的同时,玛纳斯河流域的积雪期呈现减短的趋势;该特征是47年来流域冬季平均气温与累计降水量的升高所直接驱动的结果,但两者并不具备统计学上的相关关系。

The variation of snow is very important for water management in Manasi River Basin because the melt water from snow is a vital water supply in this region.In this paper,we analyzed the variation of snow cover change between 2007 and 2008,and the julia days and snow days fluctuation between 1960 and 2006 based on the MOD10A1 snow images and the data of weather sites.The results of snow cover change between 2007 and 2008 demonstrated that there are abviously seasonal change of snow which distributed at the flat river valley;when the seasonal snow disappeared,the glacier was distribute at the tops and northwest slopes of the mountain because of its high elevation.The results of the julia days and snow days fluctuation between 1960 and 2006 reflected that there were a trend of significant postponing of julia days of snow and reducting of snow days in Manasi River Basin.The analysis of the frequency of julia days in this region between 1960 and 2006 showed that the average of julia days between 1960-1988 was the 303th day,while the average of julia days between 1994-2006 was later and the date was delayed to the 313th day in the year.At the same time,the snow days in this basin was shortened at the rate of 0.06 days / year,the rate was less than the speed of snow postpone 0.3 days / year.This variation was the result of the increasing of winter temperature and cumulative precipitation between 1960 and 2006,but there were not statistical correlations between both of them.