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Teleconnections between lower and higher latitude regions are widely known in both the Northern and Southern Hemispheres. To broaden our view of these teleconnections, we searched a reanalysis data set for evidence of a teleconnection between the Arctic Oscillation (AO) and the Antarctic Oscillation (AAO), two widely separated circumpolar phenomena. Statistical analysis of the Japanese 55-year reanalysis data set showed significant in-phase synchronization between the AO and AAO, particularly in October and February, with a vertical structure extending from the troposphere to the stratosphere. This vertical structure may suggest a stratospheric control, and we did not find a significant signature indicating a tropical ocean control. We also observed decadal-scale modulation of the synchronicity. Observational evidence implies that the stratospheric meridional circulation may be responsible for AO-AAO synchronization.

Plain Language Summary The Arctic Oscillation (AO) and the Antarctic Oscillation (AAO) are dominant atmospheric variability patterns in the Northern and Southern Hemispheres, respectively. Each is a pressure seesaw between the pole and the midlatitudes that remotely affects weather, climate, and environment around the world. We showed interhemispheric in-phase synchronization between the AO and AAO in October and February, and we also found decadal-scale variation of the synchronicity. Because the vertical structure of the AO-AAO synchronization extends from the troposphere to the stratosphere, stratospheric variations may be responsible for the synchronization. This finding of AO-AAO synchronization points the way to a better understanding of past, present, and future pole-to-pole climatic relationships and improvements in long-term weather forecasts.