赤道反气旋的合成结构和涡度收支

本文通过普查1979—1983年7—9月在10°S—15°N、90°E—140°E范围内的赤道反气旋活动情况,从中选出15个强度和范围较接近的赤道反气旋进行综合分析,得到它们的平均三维结构特征。结果表明,赤道反气旋是一个暖性的中低层系统。反气旋环流与涡度、散度及垂直运动有较好的配合。在赤道反气旋的低层,环流中心为负涡度区和辐散区,并与下沉运动区相对应,四周为正涡度和辐合区,以及上升运动区。高层正好相反。加热场与垂直运动场有较好的对应关系,中心区是干绝热下沉增温区。对涡度收支的计算表明,中低层有负涡度积累,上层有正涡度积累,局地涡度变化主要决定于散度项、平流项和垂直输送项。

THE COMPOSITE STRUCTURE AND THE VORTICITY BUDGET OF THE EQUATORIAL ANTICYCLONE

In this paper, the activities of the equatorial anticyclones, which occured during the period from July to September in the years 1979-1983 in the region (10°S-15°N, 90-140°E), were investigated. Among them, 15 anticyclones of similar strength and similar size were selected and used to do the composite analysis, the characteristics of their three-dimensional structure were obtained. The results show that the epuatorial anticyclone is a warm mid-lower layer system. Its anticyclonic circulation cooperates well with the vorticity, divergence and the vertical motion. In the lower layers of theequatorial anticyclone, there exist negative vorticity, divergence and subsidence in thecirculation center. But surrounding it are positive vorticity, convergence and ascendence.In the upper layers just opposite conditions can be seen. Heating field has good relation with the vertical movement. In the center is the diabatic heating induced by subsidence.The calculation of the vorticity budget shows that there is negative vorticity assemblage in the mid-lower layer and positive vorticity assemblage in the upper layer, and the local variation of vorticity is mainly due to the divergence term, the advection term and the vertical transport term.