夏季西太平洋副热带高压准双周振荡的动力学机制

ON THE DYNAMIC MECHANISM OF BIWEEKLY OSCILLATION OF SUBTROPICAL HIGH FOR THE WESTERN PACIFIC IN SUMMER

摘要:

本文用动力学分析的方法对西太平洋副热带高压准双周振荡的机制进行了探讨。结果表明:在东亚特定的环流条件下,东亚大陆季风雨带和南海至西太平洋地区热带雨带凝结潜热的热力强迫作用均可激发出天气尺度的准双周CISK波动,其波动动能向东亚大陆副热带地区的频散变化存在一种“自我调整”过程,从而引导西太平洋副热带高压的进退。

Abstract:

The biweekly mechanism of east-west oscillating movement of the subtropical western Pacific high is studied using the dynamic method. The result shows that the circulation conditions for East Asia is such that the synoptic biweekly CISK-wave can be initiated by thermal forcing due to latent heat condensation from monsoon rain in continental East Asia and tropical rain in the South China Sea and western Pacific. There are what it is called "self-adjusting" effect in the wave kinetc energy in its dispersive variation towards the subtropical East Asia continent, resulting in extension and/or retreat of the subtropical high in the western Pacific.