1979—2018年雅砻江中上游积雪时空变化及影响因素分析

Spatiotemporal variations of snow cover and its influencing factors in upper-middle reaches of the Yalong River from 1979 to 2018

基于1979—2018年积雪深度卫星数据及同期的格点型降水和气温观测资料,分析了雅砻江中上游积雪时空分布及其影响因子,利用相关分析法分析气候因子与地形因子对积雪深度时空分布的影响及贡献程度,采用趋势分析法研究积雪特征和气候因子的时间变化规律。结果表明:雅砻江中上游降水、气温、高程、坡度和坡向对年均雪深空间分布的贡献率分别为0.218、0.453、0.206、0.080和0.043,气候因子的贡献程度明显高于地形因子;研究区积雪期主要集中在10月至次年5月,年降水量和年均气温呈显著上升趋势,西北部和东南部积雪期变暖现象明显,绝大部分区域年均雪深表现为不明显的减少趋势;积雪深度与降水量的相关系数多为正值,与气温的相关系数均为负值,在区域中下游表现的相关性较强,各影响因子与积雪深度的相关程度由强到弱依次为气温、高程、坡度、降水和坡向。

Based on snow depth satellite data and gridded observed precipitation and air temperature data from 1979 to 2018 in the upper-middle reaches of the Yalong River,the spatiotemporal distribution of snow cover and its influencing factors were analyzed.The correlation analysis method was employed to assess the correlation of the snow depth with climatic factors(precipitation and air temperature)and terrain factors(elevation,slope,and aspect),and the contribution rate of each factor to the spatial distribution of snow depth.Trend analysis was conducted to investigate the temporal changes of snow depth and climatic factors.The results show that the contribution rates of precipitation,air temperature,elevation,slope,and aspect to the annual mean snow depth are 0.218,0.453,0.206,0.080,and 0.043,respectively,with the contributions of climatic factors to the spatial variability of snow depth being higher than those of terrain factors.Snow cover duration in the upper-middle reaches of the Yalong River usually spans from October to May of the next year.In this period,annual mean snow depth in most of the study area shows an insignificant decreasing trend,while annual precipitation and annual mean air temperature show significant increasing trends,especially in the northwest and southeast of the study area.The correlation coefficient of snow depth with precipitation across this region is mostly positive,while the correlation coefficient with air temperature is generally negative.Meanwhile,there are high correlations between snow depth and climate factors in the middle and lower parts of the study area.Air temperature has the highest correlation with snow depth,followed by elevation,slope,precipitation,and aspect.