大气环流的变化与南海夏季风活动的关系

Relationship between Westerly Jet and Summer Monsoon Activities in the South China Sea

通过对近 2 0年观测资料的计算分析表明 ,在南海夏季风活跃与中断期 ,南北半球副热带西风急流和热带东风急流以及青藏高压和墨西哥高压有明显的差异。从南半球向北传播的散度场低频振荡以及从北半球高纬向南传播的西风场低频振荡等的有利位相同时传入南海并共同作用可引起南海夏季风的活跃或中断。各种低频振荡的有利位相传播到南海并发生锁相的时间决定着南海夏季风明显的活跃或中断发生的时间。

In the view of data analyses, it is indicated that the variation of general circulation systems such as the subtropical westerly jet in both Hemispheres, the easterly jet, the Tibetan Plateau high and the Mexican high is greatly different between the period that the summer monsoon is in activity in the South China Sea (SCS) and the period that the SCS monsoon is in inactivity. The results are also shown that the activity or inactivity of the summer monsoon in the SCS is determined by the different phase of the northward propagating low frequency oscillation (LFO) of wind divergence field from the Southern Hemisphere and the phase of southward propagating LFO of westerly wind field from the Northern Hemisphere. And the phase locked of different type LFO in the SCS is the determinant factor in controlling the timing of activity of the SCS monsoon.