[A-AS07] 成層圏・対流圏過程とその気候への影響

[AAS07-16] 北太平洋ジャイア振動と冬の北半球成層圏

*山崎 孝治¹、中村 哲¹、星 一平² (1.北海道大学、2.新潟大学)

キーワード：北太平洋ジャイア振動、極渦、成層圏突然昇温、成層圏ー対流圏結合、北太平洋振動

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.