2001—2017年祁连山积雪面积时空变化特征

Temporal-spatial variation characteristics of snow cover in Qilian Mountains from 2001 to 2017

科学监测祁连山积雪面积及变化特征对该区域气候研究、雪水资源开发利用、环境灾害预报及生态环境保护等具有重要意义。基于2001—2017年MOD10A2积雪产品和气象数据,分析祁连山积雪面积动态变化特征及与气温降水关系。结果显示:(1) 2001—2017年祁连山积雪面积年际波动趋势较大,呈减小趋势,多年平均积雪面积约为5×104km2,占祁连山总面积的25. 9%;年内变化成"M"型,即在一个积雪年中有两个波峰和波谷,波峰出现在11月和1月,波谷出现在7月;季节变化波动趋势较大,夏冬季积雪面积减小趋势大于春季,秋季呈现略微增加趋势。(2)祁连山区积雪面积主要分布在3 000～4 000 m及4 000～5 000 m,积雪覆盖率随着海拔上升呈现逐渐增大的趋势;祁连山区不同坡向积雪覆盖面积差异较大,积雪覆盖率差异较小;积雪频率高值区呈典型的条带状分布,与祁连山地形相一致,呈西北—东南分布,且分布西部大于东部。(3)初步分析认为祁连山积雪面积变化对气温要素更敏感。

To monitor scientifically the snow cover and its change characteristics in the Qilian Mountains if of important significance for the regional climate research,the development and utilization of snow meltwater,the forecast of natural disasters and ecological environmental protection. Based on the MOD10A2 snow products and meteorological data from 2001 to 2017,the dynamic changes of snow cover in the Qilian Mountains and its relationship with temperature and precipitation were analyzed. The results show as follows:( 1) The average snow cover area in the Qilian Mountains was about 5 × 104km2 which accounted for 25. 9% of its total area. The snow cover between 2001 and 2017 has a large inter-annual fluctuation trend showing a pattern of letter "M " which meant the Qilian Mountains has two peaks and one trough in terms of the snow cover in a year. The peak positions appeared in November and January,and the trough appeared in July. The snow cover had a relatively large seasonal variation trend which had a bigger decreasing tendency in summer and winter than that in spring and a slight increase trend in autumn.( 2) The snow cover area in Qilian Mountains was mainly located in the places of an altitude in the range between 3 000 m and 5 000 m,and the snow cover tended to increase with the elevation. There was a big difference in snow cover area in different aspects in Qilian Mountains yet with a small snow coverage rate. The high-snow frequency zones showed a typical banded distribution which is basically consistent with the distribution of the Qilian Mountains,and the areas with high value of snow accumulation were much more in the west than those in the east.( 3) The preliminary analysis showed that the change of snow area in Qilian Mountains was more sensitive to the temperature.