江淮流域夏季降水异常与西北太平洋副热带30～60天振荡强度年际变化的联系  

Associations of Summertime Rainfall Anomalies over the Changjiang-Huaihe River Valley with the Interannual Variability of 30-60-day Oscillation Intensity in the Northwestern Pacific

作　　者：贾燕[1] 管兆勇[1] 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,大气科学学院,南京210044

出　　处：《大气科学》2010年第4期691-702,共12页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展计划项目2006CB403602;国家科技支撑计划2009BAC51B01

摘　　要：利用1978～2007年NCEP/NCAR再分析资料和地面观测站降水资料,研究了夏季江淮流域降水多寡与30～60天振荡(ISO)强度年际变化的联系。结果表明:江淮流域夏季降水异常与台湾海峡地区及西北太平洋低频能量变化相关显著。定义了ISO强度指数,对ISO强度指数高低年夏季低频降水以及低频环流的位相合成表明:高指数年主要通过存在于南海—西北太平洋地区的低频气旋、反气旋系统的交替活动来影响副热带高压的进退,从而引起江淮流域夏季降水异常;低指数年江淮流域夏季降水主要受西太平洋副热带高压位置及强度变化的影响,降水异常区主要位于江南地区。进一步研究表明,非30～60天低频降水扰动与低频振荡强度也有很好的相关。低频环流对双周以及天气时间尺度环流变化可能存在调制作用,这种作用对江淮流域夏季降水的年际异常起到非常重要的作用。Using the NCEP/NCAR reanalysis and in situ precipitation data from 1978 to 2007,the authors have investigated the associations of the interannual variability of 30-60-day intraseasonal oscillation（ISO）intensity with rainfall in the Changjiang-Huaihe River valley.The results demonstrate that the summer rainfall anomalies over the Changjiang-Huaihe River valley are significantly correlated with the changes of intensity of low-frequency oscillations in regions around the Taiwan Strait and the northwestern Pacific.An intensity index of the 30-60-day intraseasonal oscillations is defined to further examine the relationships of ISO with rainfall in eastern China.The phase composites of the low-frequency precipitation and circulation for the high-index years show that the cyclone and anticyclone appear alternatively in the northwestern Pacific,inducing the advancing or retreating of the subtropical high,and henceforth leading to the rainfall anomalies over the Changjiang-Huaihe River valley.In the low-index years,the rainfall over the Changjiang-Huaihe River valley is affected by changes of location and intensity of the western Pacific subtropical high on the intraseasonal time scale.However,precipitation anomalies in the low index years occur largely to the south of the Changjiang River valley other than in the Changjiang-Huaihe River valley.Further examinations have been carried out for both the non-30-60-day precipitation and intensity of 30-60-day oscillations,showing high correlations between them as expected.Nevertheless,both synoptic and biweekly perturbations in rainfall are possibly modulated by 30-60-day oscillations,which play very important roles in the interannual anomalies of rainfall over the Changjiang-Huaihe River valley.

关 键 词：30~60天振荡强度 年际变化 降水异常 长江淮河流域 北半球夏季 

分 类 号：P461[天文地球—大气科学及气象学]