Abstract. Pronounced quasi-decadal oscillation in surface air temperature over northern Japan is linked to the North Atlantic Oscillation (NAO). A NAO-based regression analysis reveals a hemispheric-scale decadal temperature anomaly pattern that features a seesaw between eastern Canada/Greenland and northern Eurasia at high latitudes with additional centers of action in eastern United States and North Africa/Middle East. Advection of climatological mean temperature gradient by anomalous winds seems a mechanism for these temperature anomalies. Particularly, positive temperature anomalies over the Siberia at NAO's positive phase are associated with anomalous southwesterly winds on the upstream side. The advection by mean westerlies is also important over Eurasia, bringing large decadal variability to northern Japan. This quasi-decadal oscillation can be traced farther eastward to the North Pacific, in the Aleutian low and in sea surface temperature on the subarctic front. A possible inter-oceanic link between the North Atlantic and Pacific is discussed.

・April 1999 Issue, Journal of Meteorological Society of Japan

・Also see a report in the Nihon Keizai Shimbun--a Japanese national daily newspaper--page 11, October 24, 1998




 北日本に見られる地上気温の顕著な準10年振動と北大西洋振動(NAO)との関係について調べた. NAO 指数に基づく回帰解析の結果, 高緯度域ではカナダ東部・グリーンランドと北欧・シベリアとの間に, また, 中緯度域ではアメリカ東部と北アフリカ・中東との間に、位相が逆の気温アノマリが見い出された.このような気温変化のメカニズムとして, 風のアノマリによる平均温度移流が考えられる. 特にシベリアの気温変動は東へ広がり、北日本に顕著な準10年振動をもたらしている.NAOと同調する準10年振動は、更に東側に位置する北太平洋にも見られ、特にアリューシャン低気圧や亜寒帯フロント上の海面水温に顕著に現れる.