The East Pacific Wavetrain: Its Variability and Impact on the Atmospheric Circulation in the Boreal

• 作 者: ZHOU Putian SUO Lingling YUAN Jiacan TAN Benkui
• 机 构: Department of Atmospheric and Oceanic Sciences, School of Physics,Peking University, Beijing 100871
• 出 处: 大气科学进展（英文版）
• 发表日期: 2012年3期
• 关键词: East Pacific wavetrain stationary waves vertical propagation

The East Pacific wavetrain (EPW) refers to here the intense stationary wave activity detected in the troposphere over the East Pacific and North America in 45 north winters from 1958 to 2002.The EPW is generated in the lower troposphere over the East Pacific,propagating predominantly eastward into North America and slightly upward then eventually into the stratosphere.The intensity of the EPW varies from year to year and exhibits apparent decadal variability.For the period 1958-1964,the EPW was in its second maximum,and it was weakest for the period 1965-1975,then it was strongest for the period 1976-1987.After 1987,the EPW weakened again.The intensity and position of the members (i.e.,the Aleutian low,the North American trough,and the North American ridge) of the EPW oscillate from time to time.For an active EPW versus a weak EPW,the Aleutian low deepens abnormally and shifts its center from the west to the east of the date line,in the middle and upper troposphere the East Asian trough extends eastward,and the Canadian ridge intensifies at the same tine.The opposite is true for a weak EPW.Even in the lower stratosphere,significant changes in the stationary wave patt are also observed.Interestingly the spatial variability of the EPW assumes a Pacific-North American (PNA)-like teleconnection patt. It is likely that the PNA low-frequency oscillation is a reflection of the oscillations of intensity and position of the members of the EPW in horizontal direction.