青藏高原冬春季积雪异常与西南地区夏季降水的关系

Relation between the Abnormal Snow Cover in Winter and Spring over the Tibetan Plateau and Summer Precipitation over the Southwest China

选取1961-2007年青藏高原冬、春季积雪日数资料和西南地区夏季降水资料,对高原积雪和降水作奇异值分解(SVD)分析.结果表明:冬春季高原积雪对西南地区夏季旱涝有重要的影响.冬、春季高原积雪的不同分布将造成后期西南地区夏季降水分布出现差异.西南地区夏季降水对冬季高原积雪异常最敏感的区域主要是四川东北部、重庆、西藏中西部,对春季积雪异常最敏感的区域主要位于四川东部、重庆、贵州东北部,以及西藏中东部.与降水敏感区相对应的冬季高原积雪分布的关键区是西藏中西部和青海中南部至四川西北部地区,春季则转变为西藏西部和青海部分地区.总的来说,冬季高原积雪的异常变化比春季对西南地区夏季降水的影响更为明显.因此,前期青藏高原积雪是西南地区夏季降水预测中的一个重要信号,对夏季西南地区降水有一定的指示和预测意义;冬季高原积雪日数尤其具有预报指示意义,可作为一个重要的预测指标.

By using the data set of winter and spring snow cover days over the Tibetan Plateau and summer precipitation over Southwest China from 1961 to 2007,the relationship between the snow cover and the summer precipitation are studied by Singular Value Decomposition（SVD） analysis.It is revealed that the winter and spring snow cover over the Tibetan Plateau influences the summer precipitation over Southwest China obviously.The distribution of correlation between the winter and spring snow cover days in the plateau and the summer precipitation over Southwest China has sameness,as well as significant difference.The difference in the distribution of snow cover in winter and spring will change the distribution of summer precipitation over Southwest China.The areas where the summer precipitation is most sensitive to the winter snow cover over the plateau are the northeast of Sichuan,Chongqing,mid-west of Tibet.The areas where the summer precipitation is most sensitive to the spring snow cover over the plateau are the east of Sichuan,Chongqing,northeast of Guizhou and mid-east of Tibet.The key areas of winter snow cover in the plateau,which correspond to the most sensitive of summer precipitation over Southwest China,range from the mid-west of Tibet and mid-south of Qinghai to northwest of Sichuan.The key areas of spring snow cover in the plateau,which correspond to the most sensitive of summer precipitation over Southwest China,are the west of Tibet and a small part of Qinghai.In general,the effect of winter snow cover in the plateau is more distinct than that of spring snow cover in the plateau.The winter snow cover in the plateau is an important index for forecasting summer precipitation over Southwest China.