基于MODIS积雪产品的天山年积雪日数空间分布特征研究

山区积雪是干旱区气候变化的重要指标因子，积雪日数与积雪分布之间有着密切关系。为了研究天山山区积雪日数空间分布特征，以MODIS8d积雪产品MOD10A2（Terra）和MYD10A2（Aqua）为数据源，首先对数据进行最大化合成，获取新疆天山500m×500m分辨率的年积雪日数，然后分析了2002-2014年13a积雪日的年际变化，并结合DEM数据分析了13a天山多年平均积雪日随高程和坡度的变化特征。结果表明：天山积雪日数分布极为不均，最大年平均积雪日数为193d，13a内天山绝大部分地区年积雪日变化趋势较为稳定，稳定区约占天山总面积的83.92%；在研究时段内天山总积雪日数主要集中在30d以内，其比例约为天山总面积的48%；各个高程带积雪日面积分布差异明显，但总体上积雪日数随着高程的增加而增加；从积雪日数随坡向分布来看，北坡、东北坡、东坡、西坡、西北坡所占面积比例（>30d）相对高于其他坡向。该研究结果对干旱区水资源估算具有参考意义。

A study of spatial distribution of snow cover days in the Tianshan Mountains based on MODIS snow products

Snow cover is one of the sensitive factors to climate change in arid area.There is a close relationship between snow cover days and snow cover area.In order to analyze the spatial distribution of snow cover days,eight-day synthetic data of MODIS from Terra (MOD10A2) and Aqua (MYD10A2) were used.Firstly,the snow cover days (500 m × 500 m) in Tianshan Mountains were obtained through removing the effect of cloud based on combined snow cover products of MODIS.Then,based on annual snow cover days and DEM data,the spatial and temporal variabilities of snow cover days with elevation and aspect from 2002 through 2014 were analyzed.The results show that the distribution of snow cover days had been extremely uneven.The maximum annual mean snow cover days were 193 days.The snow cover days in 83.92％ area of the Tianshan Mountains had changed little during the 13 years.About 48％ snow cover days was no more than 30 days.The snow cover days had increased with elevation,with a large spatial difference.More snow cover days (＞ 30 d) were gathered in the north,northeast,east,west and northwest aspects.This study will be useful for estimating water resources in arid areas.