Angular Momenta of the Antarctic and the Arctic Oscillations

Abstract

The angular momentum anomalies associated with the Antarctic and Arctic Oscillations are examined in a coupled general circulation model. The size of the global-mean anomaly of the Ω angular momentum is unexpectedly larger than that of the relative angular momentum. The result is a simple consequence of mass conservation. Since the mass anomaly at high latitudes is equal and opposite to that at low latitudes, and since the high-latitude mass anomaly is relatively close to the rotation axis, the global-mean Ω angular momentum is significantly nonzero. Analysis of the meridional mass transport indicates that the Antarctic and Arctic Oscillations are persistent but damped modes.