夏季南海区域赤道西风与热带扰动的相互作用

THE INTERACTION BETWEEN EQUATORIAL WESTERLIES AND TROPICAL DISTURBANCE OVER THE REGION OF SOUTH CHINA SEA IN SUMMER

摘要:

本文分析了1973—1984年6—9月南海地区赤道西风与热带扰动的活动情况,结果表明,赤道西风对热带扰动的发生发展有一定的贡献,而热带扰动的发展又反过来使其南侧的赤道西风进一步增强,赤道西风的增强往往导致热带扰动移向的改变。这种相互作用过程,存在着能量的输送。本文参照水平运动方程和涡度方程,推导得赤道西风变化率方程,说明局地赤道西风变化主要取决于总能量和涡动的输送。分析还发现,赤道西风变化率与赤道西风值有超前相关关系,借此可估计赤道西风和热带扰动的演变趋势。

Abstract:

In this paper, the equatorial westerlies (E/W) and tropical disturbances (T/D) over the South China Sea are investigated for June-September, 1973-1984. The result shows that E/ W contributes to some extent to the generation and development of T/D, the latter, in return, further enhances the south E/W of T/D,which tends to cause T/D to change its direction of motion. There is a transfer of energy in this process of interaction. Referring to the equations of horizontal motion and vorticity, the variability of E/W is derived, and they indicate a major dependence of the local change in E/W upon the transportation of general amount of energy and vorticity. It is also found that there is a leading correlation between the variability and value for E/W, by which estimates can be made for the evolving tendency of the equatorial westerlies and tropical disturbances.