地形对天山积雪冻融变化的影响分析

Analysis of the terrain effect on snow cover accumulating and melting in the Tianshan Mountains

天山积雪是新疆水资源的重要来源,地形对积雪的空间分布和消融有重要影响,分析地形对天山积雪冻融过程的影响具有重要的理论意义.基于2005-2014年的MODIS/Terra积雪8 d合成数据(MOD10A2)与数字高程模型(DEM)数据,分析了天山积雪覆盖随高程、坡度和坡向的季节变化规律.分析结果表明:(1)在不同季节里,不同高程中的融雪和积雪过程同步发生,其中在春季和冬季,雪盖变化较大的区域主要分布在低海拔和高海拔地区;而在夏、秋两季,雪盖变化较大的区域主要分布在中海拔地区.(2)在不同季节,不同坡度的积雪冻融过程也同步进行,但春季和冬季积雪呈线性变化,在缓坡和陡坡地区变化明显;夏季和秋季积雪变化缓慢,在中坡变化显著.(3)天山积雪变化随坡向具有对称性和周期性.积雪变化呈现北坡大、南坡小,春、冬季大,夏、秋季小的特点.在波动周期内,夏秋季积雪变化波动较大,变化趋势与春、冬季相反.研究结果可为融雪型洪水预报提供科学依据.

Snow cover in the Tianshan Mountains is an important water resources of Xinjiang Uygur Autonomous Region. Topography plays a major role in spatial distribution and accumulation and melt processes of snow cover, so there is an important theoretical significance to analyze the effect of terrain. Based on the eight-day synthetic data of snow cover （MOD10A2） during 2005 -2014 from MODIS/Terra and the digital elevation model （DEM）, the seasonal variation of snow cover in the Tianshan Mountains with elevation, slope and aspect was analyzed. The results show that： （1） accumulating and melting of snow occur all the time. In spring and winter, snow cover changes in the low and high altitude ranges more than that in the middle altitude range. In summer and autumn, the change occurs more in the middle altitude range. （2） Seasonal snow accumulating and melting occurs in different slopes all the time. Snow accumulating and melting have a linear relationship with slopes in spring and winter, which change significantly in the area with gentle and steep slopes. However, there is only a little change in summer and autumn. （3） There is symmetry and periodicity in the variation of snow cover in the Tianshan Mountains with the aspect. The change of snow cover mostly appears in the northern slopes in spring and winter, but the opposite case appears in summer and autumn. The change of snow cover is greater in summer and autumn than in spring and winter. This result could provide scientific basis for forecasting snow melting flood.