华北夏季旱涝的前期环流异常及其与北太平洋海温的关系

ATMOSPHERIC CIRCULATION ANOMALY PRIOR TO DROUGHT/ FLOOD OF SUMMER IN NORTH CHINA AND ITS RELATIONS TO NORTH PACIFIC SST

文章分析了华北地区夏季旱涝的前期春季大气环流和北太平洋海温异常（ＳＳＴＡ）分布特征，探讨ＳＳＴＡ与异常环流的关系，并用ＯＳＵ－ＡＧＣＭ进行黑潮地区热源异常强迫的数值试验．结果表明，当春季北极低涡明显减弱，欧亚大陆中高纬度地区纬向环流加强，西太平洋副高位置偏北偏西，且存在负ＰＮＡ型异常环流时，华北地区夏季多雨涝；反之则少雨干旱．此时，西北太平洋和赤道东太平洋ＳＳＴ分别存在较大的正、负异常，它们与春季环流异常密切相关，黑潮区ＳＳＴＡ对北半球副热带及其以北的大气环流产生显著影响，正的ＳＳＴＡ是造成华北夏涝年的前期春季异常环流形势的重要因素．

The atmospheric circulation anomaly and North Pacific SSTA in spring prior to drought/flood of summer in North China are analysed and the relationships between SSTA and atmospheric circulation anomaly are discussed. Then numerical simulation forced by heat source anomaly in Kuroshio current area is made by using OSU AGCM. The results show that rainy summers in North China would occur if arctic low vortices weaken significantly and zonal circulations strengthen in middle high latitudes in Eurasian continent and West Pacific subtropical high lies northerly and westerly, and remarkable negative PNA pattern exists in springs. Otherwise, there would be dry summers in North China. At the same period positive and negtive SST departures exist in the Western North Pacific and in equatorial East Pacific, respectively, which is closely related to atmospheric circulation anomaly in springs. SSTA in Kuroshio current area has great influence upon subtropical atmospheric circulations as well as those of its northside in the Northern Hemisphere. Positive SSTA in Kuroshio current area is an important factor for the anomalous atmospheric circulation pattern prior to flood of summer in North China.