摘要
利用合成、EOF分析、数值模拟等方法,研究了夏季欧亚中高纬两类典型持续流型:E型(主要特点是乌拉尔山、贝加尔湖、鄂霍次克海地区分别为长波脊、槽、脊)和C型(槽脊位置与E型相反)的季节内气候特征,得到以下主要结论:(1)流型指数实际分布频数与正态分布理论概率的差值呈现双峰特征,E、C型异常环流实际发生频数较理论值偏多;(2)气候平均的夏季欧亚环流型呈现明显的季内阶段性演变特征,经历着与西太平洋副高北跳、我国夏季雨带北移类似的阶段性变化,数值模拟再现了这种特征;(3)E、C型过程期间不仅欧亚中高纬区环流有明显差异,在北半球的其他地区也有明显差异。E、C型持续流型的出现和变化,与东亚太平洋(EAP)型的正负位相、南亚高压的两种模态以及西太平洋副高都有明显的相关性,是了解欧亚不同纬度带系统相互作用及其成因的一个新的着眼点。
By using synthesis,EOF analysis,numerical simulation and the other methods,this paper investigate the intraseasonal climate characteristics of two typical persistent flow patterns,pattern E （there are a longwave ridge,trough,ridge over the Ural Mountains,Lake Baikal,the Sea of Okhotsk,respectively） and pattern C （the positions of trough and ridge is opposite to pattern E＇s）,over Eurasian middle and high latitudes in summer. The main conclusions are as follows：（1） The deviation of the actual frequency from the theoretic normal distribution probability of the circulation pattern index shows a bimodal feature,i.e.,the actual frequency of patterns E and C is more than the theoretical value.（2） The indices averaged over 1959-2000 presents obviously an intraseasonal staggered variation in resemblance to the northward advance of the subtropical high over the western Pacific and summertime rain belt in China. The result of numerical simulation shows this feature too. （3） The obvious contrast between pattern E and pattern C exists not only over Eurasian middle and high latitudes but also over the other areas of the Northern Hemisphere. The occurrence and change of these persistent anomalous circulations are closely correlated with the positive and negative phases of the East Asia-Pacific （EAP） pattern,as well as the two modes of the South Asia high and the western Pacific subtropical high. It is a new focus for understanding the interaction of the systems over different latitudes of Eurasia and its cause of formation.
出处
《大气科学》
CSCD
北大核心
2009年第2期300-312,共13页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40523001
40575024
国家重点基础研究发展规划项目2006CB403601
关键词
欧亚中高纬
持续异常
季节内演变
数值模拟
Eurasian middle and high latitudes,persistent anomaly,intraseasonal variation,numerical simulation
