夏季西风带定常扰动对东北亚阻塞高压的影响

Influence of the Stationary Disturbance in the Westerlies on the Blocking Highs over the Northeastern Asia in Summer

利用 Ｅ Ｃ Ｍ Ｗ Ｆ１９８０ ～１９８８ 年９ 年的格点资料， 分析了定常扰动与东北亚阻塞高压之间的关系。分析结果表明： 定常扰动的分布对阻塞高压维持日数有着重要的影响， 定常扰动的季节变化可以很好地说明阻塞高压冬季多在太平洋和大西洋上发生和维持， 而夏季多在东北亚地区发生和维持的特征。此外， 从定常扰动的分布可以看到， 不仅中高纬地区上空的正距平强度可以影响着阻塞高压的发生和维持， 其南侧的负距平强度也同样重要地影响着阻塞高压。分析结果还表明： 不仅定常扰动的水平结构对阻高有着重要影响， 其垂直结构亦有着重要影响。最后， 对夏季定常扰动进行了波数域分析， 表明在夏季定常扰动的作用主要通过其中所包含的行星波、特别是行星波１ 波来实现， 定常扰动中行星波部分的振幅变化是影响阻塞高压发生和维持的重要物理机制。

The relationship between the stationary disturbance and the blocking highs over the Northeastern Asia is analyzed by the use of ECMWF grid data from 1980 to 1988 The analyzed results show that the distribution of stationary disturbance influences greatly the number of blocked days, the seasonal variations of stationary disturbance are in a good agreement with the fact that blocking highs occur frequently over the Pacific and the Atlantic in winter, and frequently over the Northeastern Asia in summer. Furthermore, the distribution of the stationary disturbance shows that not only the strength of the positive anomaly over the mid-high latitudes, but also the strength of the negative anomaly in the south influences the frequency of the blocking highs. The analyzed results also show that both horizontal and vertical structures of the stationary disturbance play an important role in the frequency of the blocking highs. Finally, energetic examinations on the stationary disturbance in summer show that the roles of the stationary disturbance are mainly taken by the components of planetary waves, especially wavenumber 1 The variation in the amplitude of planetary waves is in agreement with the frequency of blocking highs.