【摘要】 利用1979~2003年的NCEP/NCAR再分析资料探讨了亚澳季风区经向气流的季节性分支和结构特征.结果表明,亚澳季风区经向气流的垂直斜压结构由冬到夏发生季节性转向,即从冬季时的低层北风、高层南风转换为夏季时的低层南风、高层北风.季节反向的经向气流主体偏向北半球,其区域差异性在对流层中低层更为显著.以印度半岛和中南半岛为界,亚洲热带季风区中低层经向气流在冬夏季均呈现三通道特征,与此相应,亚澳季风区自西向东存在三支相对独立的经向环流分支,且冬夏季的差异均很显著,如冬季的中心高度自西向东递减、夏季的经向跨度自西向东递增等.更多还原

【Abstract】 Using the NCEP/NCAR reanalysis data for the period of 1979～2003, climatological characteristics of seasonal cycle and regional structure of the meridional flow associated with the Asian-Australian monsoon system are investigated. The results show that meridional flows in the Asian-Australian monsoon region display a seasonal reverse of the baroclinic structure in vertical direction, characterized by transition from low-level northerlies and high-level southerlies in boreal winter to low-level southerlies and high-level northerlies in boreal summer. The meridional flows with seasonal reverse mainly distribute over the Asian monsoon region and equatorial neighborhood, which exhibit significant regionality in the middle and lower troposphere. Consistent with three channels of meridional flows in the middle and lower troposphere over the Asian tropical monsoon region, three branches of meridional circulation are relatively independed, which are approximately divided by 75°E and 100°E and arranged from west to east in the Asian-Australian monsoon region. There are obvious differences among them in both winter and summer, such as eastward lowering of the meridional circulation center in boreal winter and eastward rising of the meridional circulation range in boreal summer.更多还原