Interhemispheric Synchronization Between the AO and the AAO

Abstract

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.