四川盆地夏季降水区域差异及其与季风的联系初探

摘要

Daily meteorological data of Sichuan Basin and NCEP/NCAR reanalysis data are employed to di-agnose the influences of East Asian and plateau summer monsoon on the summer rainfall of Sichuan Basin. The results show that the summer rainfall series of the western and eastern basin and the correlation distri-bution of summer rainfall over the whole China have similar distribution with the rain pattern Ⅰand Ⅱre-spectively.To further understand the effect of East Asian and plateau summer monsoon on the rainfall of the basin,regressive analysis is performed.First the circulation field related to East Asian summer mon-soon is obtained,then after the part of East Asian summer monsoon is removed from the circulation field using the regression method,the circulation field related to plateau summer monsoon is yielded,which is statistically independent of East Asian summer monsoon.Using the 1961 and 1998 circulation fields as ex-amples to analyze the influences of East Asian and plateau summer monsoon,it is found that both East A-sian summer monsoon and plateau summer monsoon have important influences on the rainfall of Sichuan Basin,of which the rainfall of western part is mainly related to plateau monsoon,and the summer rainfall of eastern part mainly is related to both East Asian and plateau summer monsoon,but East Asian monsoon is predominant.%基于四川盆地逐日气象观测资料、NCEP/NCAR再分析资料，分析了近46年四川盆地夏季降水变化的区域差异及其与东亚夏季风和高原夏季风的联系。结果表明：盆西和盆东夏季降水序列与全国夏季降水的相关分布分别与我国夏季降水第Ⅰ、Ⅱ类雨型分布相类似。使用一元回归方法，分别得到了与东亚夏季风和高原夏季风相关的环流场，通过对两个环流场季风指数高低值年份的合成分析发现，东亚夏季风的影响主要体现在西北气流和东南气流的辐合带在我国东部地区位置变动以及强度变化；高原夏季风对环流场的影响体现在华北到河套地区一带风向的转换。着重分析了1961和1998年夏季与东亚、高原夏季风相关的环流场，发现东亚夏季风与高原夏季风都对四川盆地夏季降水有重要影响，其中盆西夏季降水主要与高原夏季风有关，盆东夏季降水与东亚夏季风和高原夏季风都有关，但以东亚夏季风为主。