Quasi-stationary ENSO wave signals versus the Antarctic Circumpolar Wave scenario

Two conflicting views on the causal mechanism of the Antarctic interannual variability often appear in the literature, i.e., whether it is remotely teleconnected to tropical ENSO events or is a self-sustained eastward propagating circumpolar wave generated locally by an ocean-atmosphere coupling mechanism. Using a Fourier decomposition into stationary and propagating components of several oceanic and atmospheric variables, we show that most of the Antarctic interannual variability can be explained by a geographically phase-locked standing wave train linked to tropical ENSO episodes. This ENSO-modulated quasi-stationary variability is not zonally uniform, rather, the strongest ENSO impact is consistently concentrated in the Pacific sector of the Southern Ocean. The eastward propagating wave component is found to be not only minor (25% of variability) but also intermittent in phase, yielding little support for the so-called Antarctic Circumpolar Wave scenario.