基于SSM/I和MODIS数据的天山山区积雪深度时空特征分析

Spatial and temporal characteristics of snow depth in the Tianshan Mountains derived from SSM/I and MODIS data

以天山山区为研究区,利用MODIS 8d最大积雪合成数据MOD10A2,分析天山山区积雪的时间变化和空间变化情况以及不同高程带的积雪覆盖率的变化情况;结合SSM/I亮温数据和站点观测数据建立的雪深反演模型并反演研究区的雪深,根据研究区的地势起伏情况,提取特殊地形进行分析其雪深变化情况,进一步分析整个天山山区的积雪深度的时空特征,并对结果进行验证,并且对不同高程带的积雪深度进行分析.研究结果表明：1）天山山区积雪面积分布的趋势表现为自西向东、自北向南减少,总体是呈波动中减少的趋势,到了2012年天山山区年最大积雪面积为37.69×104km2.2）积雪覆盖率与高程呈正比,在高山区可达70%以上.积雪深度分布呈自西向东、由北向南减少,深度最大的是在天山北部的博格达峰、河源峰附近,可以达到80 cm以上,最小在哈密地区的托木尔提峰附近积雪深度仅在10 cm左右.积雪深度与海拔呈正相关,最大雪深出现在4 500 m以上的高山区.3）对雪深反演结果的精度评价表明,模型在10～30 cm雪深范围内,反演平均误差为-2.47 cm;在雪深〈10 cm或〉30 cm的局部地区存在较大偏差.

This study focus on the temporal and spatial variations of snowcover and change rate in different elevation zones of the Tianshan Mountains by using the MOD10A2 snowsynthetic data,from 2003 to 2012. Furthermore,the brightness temperature data of SSM/ I and the station-based observation data are used to build up a snowdepth retrieval model to compute the snowdepth for the study area. Eventually,the spatial and temporal variations of snowdepth for the whole Tainshan Mountains and accuracy validation were carried out based on the relief of the Tianshan Mountains The study result shows that there are clear spatial and temporal distributed patterns：（ 1） spatially,the overall distribution pattern of the snowcover area in the Tianshan Mountains is decreasing from west to east and from north to south,with the maximum snowdepth of 80 cm nearby the Mt.Bogda and Heyuan Peak in the north of the Tianshan Mountain and the maximum snowcover area was 37. 69 ×104km2in 2012;（ 2） temporally,the snowcover area is fluctuating with a little decreasing tendency;（ 3） the accuracy evaluation of snowdepth shows that the snowdepth between 10 cm and 30 cm have relatively higher accuracy with an average error of 2. 47 cm,and,on the contrary,the areas with snowdepth less than 10 cm and greater than 30 cm have relatively larger deviation.