Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Oral

A (Atmospheric and Hydrospheric Sciences) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS07] Stratosphere-troposphere Processes And their Role in Climate

Wed. May 23, 2018 1:45 PM - 3:15 PM A07 (Tokyo Bay Makuhari Hall)

convener:Shingo Watanabe(Japan Agency for Marine-Earth Science and Technology), Yoshio Kawatani(Japan Agency for Marine-Earth Science and Technology), Takashi Sekiya(国立研究開発法人 海洋研究開発機構, 共同), Kaoru Sato(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Chairperson:Watanabe Shingo(海洋研究開発機構)

2:30 PM - 2:45 PM

[AAS07-16] The North Pacific Gyre Oscillation and northern hemisphere stratosphere in winter

*Koji Yamazaki1, Tetsu Nakamura1, Kazuhira Hoshi2 (1.Hokkaido University, 2.Niigata University)

Keywords:North Pacific Gyre Oscillation, polar vortex, sudden stratospheric warming, stratosphere-troposphere coupling, North Pacific Oscillation

The North Pacific Gyre Oscillation (NPGO) is the 2nd EOF mode of northeast Pacific sea surface temperature/sea surafce height. The NPGO is associated with the atmospheric dipole pattern named North Pacific Oscillation. The relationship between the NPGO and the winter stratospheric circulation is examined by using the ERAinterim reanalysis dataset from 1979 to 2016. It is found that the winter polar vortex in the Arctic stratosphere is weak in the positive NPGO years, in particular in December. The major sudden stratospheric warming (SSW) before early January only occurs in the positive NPGO years. Moreover, the SSWs in the positive NPGO years show both wavenumber 1 and 2 signatures and propagate to the troposphere, while those in the negative NPGO years show only wavenumber 1 signature and do not propagate to the troposphere.