欧亚大陆积雪两种物理效应对2010年春末夏初华南降水的影响

Two Physical Effects of Eurasian Snow Cover on the Late-Spring and Early-Summer Rainfall in South China of 2010

本文基于欧亚大陆积雪深度资料和中国台站降水资料的奇异值分析(SVD)结果,使用大气环流模式(CAM3.1)分别进行三组集合试验来研究欧亚大陆积雪的反照率效应和水文效应对2010年5～6月华南降水的影响:第一组试验综合考虑积雪的两种物理效应,既有反照率效应又有水文效应;第二组试验仅考虑积雪反照率效应,忽略水文效应;第三组试验只考虑积雪水文效应,忽略反照率效应。试验结果表明,积雪的两种物理效应都会对后期华南降水产生影响,但是三组试验中积雪不同物理效应所导致的异常幅度和范围存在较大差异,其中积雪水文效应比反照率效应引起的变化幅度大。当两种效应共同作用时产生的异常与统计分析结果最为接近,变化幅度也最大,但是并不等于单纯反照率效应和单纯水文效应作用之和。

This study investigated the snow albedo and hydrological effects on the precipitation in South China in 2010, based on the singular value decomposition （SVD） analysis of the Eurasian snow depth dataset and the 160-station rainfall dataset in China. Three ensemble simulations were conducted by using community atmosphere model 3.1 （CAM3.1）. The first ensemble simulation includes both the snow albedo and the snow hydrological effect. The second ensemble simulation only considers the snow albedo effect but ignores the hydrological effect. The third ensemble simulation only considers the snow hydrological effect but ignores the albedo effect. The results indicate that both these effects could have impacts on the South China rainfall. However, there are great differences in amplitudes and ranges of abnormities induced by those three simulations. The magnitude of abnormities caused by the snow hydrological effect is larger than that by the albedo effect. When those two effects work together, the result agrees well with observations and the magnitude is the largest. However, the magnitude is not equal to the sum of that caused by the snow albedo and hydrological effects respectively.