北半球大气环流的纬向对称模态  

Zonally Symmetric Modes of Northern Hemisphere General Circulation

作　　者：郭品文[1] 刘畅[1] 

机构地区：[1]南京信息工程大学江苏省气象灾害重点实验室,江苏南京210044

出　　处：《南京气象学院学报》2008年第3期293-299,共7页Journal of Nanjing Institute of Meteorology

基　　金：江苏省高校自然科学研究计划(05KJB170072)

摘　　要：运用自然正交分解方法(EOF)提取了北半球冬季热带外地区标准化纬向平均纬向风场的前两个模态。第1模态(方差贡献为34%)表现为中高纬带的西风(东风)异常和中纬带的东风(西风)异常,与之相联系的海平面气压场的异常表现为极区与中高纬度地区海平面气压场的反位相变化,即北极涛动(AO);第2模态(方差贡献为21%)表现为中纬带的西风(东风)异常和中低纬带的东风(西风)异常,与之相联系的海平面气压场的异常表现为副极地地区与副热带地区海平面气压场的反位相变化,即副热带涛动STO(sub-tropical oscillation)。副热带涛动的水平结构表现出较强的纬向对称性,垂直方向上表现出相当正压性;与副热带涛动正位相相联系的纬向平均温度场表现为中高纬度地区负异常和副热带地区正异常,而且费雷尔环流加强南移。副热带涛动不仅在冬季有所表现,而且在整个冬半年(11月—翌年4月)都有所表现,但在夏半年则不存在。The two important modes of standardized wintertime zonal-mean zonal wind in Northern extratropics are extracted using the method of empirical orthogonal function （EOF）. The leading mode （explaining 34% of the variance）is characterized by anomalous westerly（easterly） in high-middle latitudes and anomalous easterly （westerly） in mid-latitudes, and the antiphase variations of SLP anomalies between polar regions and high-middle latitudes. The leading mode is Arctic Oscillation（AO）. The second mode defined as sub-tropical oscillation （STO） （explaining 21% of the variance） emerges as anomalous westerly （easterly） in mid-latitude regions and easterly （westerly） in middle-low latitude regions and shows opposite variations of SLP anomalies between sub-polar regions and sub-tropics. The spatial structure of STO is studied. The results indicate that STO shows a prominent zonally symmetric structure in the horizontal and a quasi-barotropic structure in the vertical. The zonal-mean temperature field associated with a positive phase of STO shows negative anomalies in high-middle latitudes and positive anomalies in sub-tropics, and the enhanced Ferrel moves equator-ward. We still concluded that STO can both be found in winter or the whole winter half year,but not in the summer half year.

关 键 词：副热带涛动 纬向对称 经向偶极子 

分 类 号：P434[天文地球—大气科学及气象学]