Advances in Atmospheric Sciences

, Volume 29, Issue 3, pp 471–483

The East Pacific Wavetrain: Its variability and impact on the atmospheric circulation in the boreal winter

  • Putian Zhou周普天
  • Lingling Suo所玲玲
  • Jiacan Yuan袁嘉灿
  • Benkui Tan谭本馗
Article

DOI: 10.1007/s00376-011-0216-3

Cite this article as:
Zhou, P., Suo, L., Yuan, J. et al. Adv. Atmos. Sci. (2012) 29: 471. doi:10.1007/s00376-011-0216-3

Abstract

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 northern 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 time. The opposite is true for a weak EPW. Even in the lower stratosphere, significant changes in the stationary wave pattern are also observed.

Interestingly the spatial variability of the EPW assumes a Pacific-North American (PNA)-like teleconnection pattern. 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.

Key words

East Pacific wavetrainstationary wavesvertical propagation

Copyright information

© Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Putian Zhou周普天
    • 1
  • Lingling Suo所玲玲
    • 1
    • 2
    • 3
  • Jiacan Yuan袁嘉灿
    • 1
  • Benkui Tan谭本馗
    • 1
  1. 1.Department of Atmospheric and Oceanic Sciences, School of PhysicsPeking UniversityBeijingChina
  2. 2.Nansen Environmental and Remote Sensing CenterBergenNorway
  3. 3.Bjerknes Center for Climate ResearchBergenNorway