秋季亚洲-太平洋涛动与中国近海热带气旋活动的关系

A study of the relationship between the Asian Pacific oscillation and tropical cyclone activities over the coastal waters of China during autumn

中文关键词:  亚洲-太平洋涛动， 秋季， 东亚大气环流， 热带气旋

英文关键词:Asian Pacific Oscillation (APO), Autumn, East Asia atmospheric circulation, Tropical cyclone

中文摘要:

      采用联合台风警报中心的台风最佳路径资料和NCEP/NCAR再分析资料，分析了秋季（9—10月）亚洲 太平洋涛动（APO）强度的年际变化与东亚 太平洋大气环流的关系，探讨了APO与西北太平洋和中国近海热带气旋（TC）活动的关系。结果表明：秋季APO年际变化与同期西北太平洋和中国近海TC活动关系紧密，即当APO偏强（弱），西北太平洋TC活跃区明显偏西（东），中国近海TC偏多（少）；APO可以通过影响中国近海对流层纬向风垂直切变、低层辐合和对流层中层引导气流等，从而影响西北太平洋和中国近海TC活动；当APO偏强（弱）时，东亚大槽偏弱（强），东亚冬季风偏弱（强），使得侵入中国近海和热带西北太平洋的冷空气活动偏弱（强），有（不）利于这些海域TC的生成和发展；此外，在APO偏强时，西太平洋副热带高压脊偏西，其南侧偏东气流加强，有利于TC在偏强的偏东气流引导下向西移动或者其转向点偏西；而在APO弱年，副热带高压脊偏弱和偏东，偏东引导气流减弱，不利于TC西行或有利于其转向点偏东。

英文摘要:

      Using the datasets from the JTWC optimal typhoon tracks and the NCEP/NCAR reanalysis data, we investigate the interannual variability of the autumn (September and October) Asian Pacific Oscillation (APO) and its relationships with the atmospheric circulation over the Asian Pacific region and tropical cyclone (TC) activities over the western North Pacific and the coastal waters of China. The results show that the interannual variability of the APO is closely related to the TC activity over the western North Pacific and the coastal waters of China during autumn. Corresponding to stronger (weaker) APO, the TC often appears in a more westward (eastward) position and there is a more (less) TC number in the coastal waters of China. The APO may affect the vertical shear of the zonal wind between high and low levels of the troposphere, the lower tropospheric convergence, and the mid tropospheric steering current over the coastal waters of China and thus the TC activity over the western North Pacific and the coastal waters of China. When the APO is stronger (weaker), the long wave trough over the extratropics of East Asia is weaker (stronger) and the East Asian winter monsoon is weaker (stronger), accompanying the invasion of weaker (stronger) cold masses into the tropical western North Pacific and the coastal waters of China, favoring (not favoring) the occurrence and development of the TC over these seas. Moreover, corresponding to stronger APO, the subtropical ridge over the western North Pacific is located in a more westward position and the easterly current south of the ridge is stronger, which favors the TC to move westwards along the stronger easterly steering current or most likely causes the TC to turn its moving direction in a more westward position. Corresponding to weaker APO, the ridge is weaker and located in a more eastward position, the easterly steering current is weaker, both of which does not favor the TC to move westwards or favors the TC to change the direction in a more eastern position.