A Hemispheric-Scale Quasi-Decadal Oscillation and Its Signature in Northern Japan

[摘要] 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 the eastern United States and North Africa/Middle East. Advection of climatological mean temperature gradient by anomalous winds seems to be a mechanism for these temperature anomalies. Particularly, positive temperature anomalies over 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.

[学科分类] 大气科学