梅雨期温带急流变化与中高纬环流系统的关系

The relationship between the East Asian polar front jet and mid-high latitude circulation during Meiyu season

利用NCEP/NCAR再分析资料分析了与温带急流相关联的梅雨期东亚上空中高纬环流系统的变化特征,揭示出东亚高空急流经向分量在急流变化中具有重要作用,温带急流区经向风和东亚中高纬槽脊关系密切。在温带急流由强变弱的过程中,当温带急流强度强时,急流区以纬向风为主导;当温带急流强度弱时,经向风增强,纬向风迅速减弱,急流区以经向风为主导。温带急流区纬向风强时,500 hPa位势高度等值线平直,中高纬环流为纬向型;温带急流区经向风强时,中高纬槽脊系统发展,中高纬环流由纬向型转换为经向型。梅雨期温带急流区经向风异常主要有80°E、100°E、120°E、140°E四个中心,温带急流区经向风异常的位置不同时,中高纬阻塞高压出现位置不同,冷空气路径不同。

The relationship between the East Asian polar front jet(EAPJ)and mid-high latitude circulation systems in East Asia is investigated based on the daily NCEP-NCAR reanalysis dataset.The results show that the meridional component of the EAPJ plays an important role in the change of East Asian jet stream,which accompanied with the mid-high latitude trough and ridge.Through the zonal wind dominates in the jet region when the EAPJ is strong.The meridional wind increases rapidly and becomes the dominant wind when the EAPJ decreases.Meanwhile,the trough-ridge systems are more intense,and the mid-high latitude circulation changes from zonal type to meridional type.Further analysis reveals that there are four centers of meridional wind anomalies in the EAPJ region:80°E,100°E,120°E and140°E,corresponding to four different mid-high latitude blocking locations and cold air paths.