前期北太平洋海温异常对贵州夏季降水的影响

Impact of SST in Northern Pacific Ocean on Flood Season Precipitation in Guizhou

利用1979 2011年夏季贵州83个台站降水月资料及前期北太平洋逐月海温资料,对二者的耦合关系进行了SVD分析,对异常年份进行了合成分析,并对前期海温影响贵州夏季降水的可能机制进行了探讨。结果表明:(1)影响贵州夏季降水的海温关键区,从前一年夏季至当年春季由北太平洋的加利福尼亚冷流区转移到了黑潮区,前一年夏、秋及冬季海温的变化与贵州夏季降水关系更为密切,同期春季与贵州夏季降水的相关最差,且前期北太平洋海温与贵州中东部降水的异性相关更好。(2)贵州夏季降水偏多年,前一年夏季北太平洋海温分布从西北到东南为"+-+"分布,而降水偏少年为"-+-"分布,降水偏多年与El Nino事件关系不密切,而降水偏少年与La Nina事件关系较密切;在北太平洋夏季海温正异常年翌年,贵州夏季降水呈全区一致的偏多,而在负异常年翌年,贵州夏季降水呈全区一致的偏少。(3)前期北太平洋海温异常是影响贵州夏季降水的可能机制,北太平洋海温异常升高可引起向中纬度西太平洋传播的波列,通过加强西风造成西太平洋副热带高压西伸、偏强,有利于贵州降水异常偏多;而北太平洋海温异常降低对贵州降水的影响不如海温异常显著,它可造成西风减弱,使得西太平洋副热带高压东退、偏弱,从而抑制贵州夏季降水。

Based on the precipitation of summer at 83 stations in Guizhou from 1979 to 2011 and the mean monthly reanalysis SST data,the relationship between summer precipitation and the SST in the Pacific Ocean are investigated in terms of SVD. The results are as follows:( 1) The key SST region which influencing precipitation in Guizhou from California cold current to Kuroshio from previous summer to spring,the relationship between SST in spring and precipitation in Guizou is not close,the relationship between the previous SST and precipitation in the middle-east of Guizhou is closer.( 2) Composite analysis results are as follows: In flood year,the distribution of Northern Pacific Ocean SST from west-north to east-south is‘+- + ',but in drought year the distribution of Northern Pacific Ocean SST from west-north to east-south is ‘- +- ',the relationship between rainfall rich and El Nino events isn' t close,but the relationship between rainfall deficit and La Nina event is close.( 3) The possible mechanism that the influence of previous Northern Pacific Ocean SST on precipitation in Guizhou: Northern Pacific Ocean SST rising can cause wave train spreading to the middle Western Pacific Ocean,which making the Western Pacific subtropical high moving to west,benefiting to rainfall; the influence of Northern Pacific Ocean SST dropping was not as good as those caused by SST rising,it can cause Western Pacific subtropical high moving to east,not benefiting to rainfall.