热带海表温度持续异常对东亚初夏大气环流的影响

Effect of Persistent Anomaly of Sea Surface Temperature in Tropical Ocean on Atmospheric Circulation in Early Summer in East Asia

利用NCEP/NCAR月平均海表温度及北半球大气环流分析资料,系统研究了热带海洋表面温度持续异常状况下东亚初夏(5、6月份)大气环流的异常特征。研究发现,暖海温年,南亚高压、西太平洋副热带高压明显偏强,冷海温年明显偏弱;暖海温年,欧亚大陆南支西风急流明显减弱北移,东亚大陆对流层低层温度偏高或接近常年,青藏高原近地面温度偏高,而冷海温年,东亚大陆对流层低层温度偏低,5月份青藏高原近地面温度偏低。研究表明。

By the use of monthly mean sea surface temperature anomaly （SSTA） data and reanalysis data from NCAR/NCEP, study of circulation transformation characteristics in the early summer （May or June） in East Asia under the conditions of persistent SSTA is conducted. The results indicate that in the warmer SSTA years, South Asia high and the subtropical high over western Pacific enhanced obviously, in contrast, in colder SSTA years. Subtropical westerly jet of the Northern Hemisphere over Asia-Europe land weakens and shifts northward clearly in warmer years, contemporary, temperature in lower troposphere over East Asia land is higher than or closes to normal, near surface temperature over the Tibetan Plateau is also above normal, while in colder years, temperature mentioned above is lower than or closes to normal, especially for temperature over the Plateau in May. It suggests that persistent SSTA are of great influence to seasonal transitions for East Asia in early summer.