Abstract

The Antarctic Circumpolar Wave (ACW) was first characterized from limited observations as a series of phase-linked propagating wavenumber 2 disturbances in sea level pressure, sea surface temperature, and sea-ice extent. This research therefore tries to determine which physical mechanisms is responsible for generating ACW-like variability. The generalized stability theory was applied to a model of the Southern Hemisphere extratropical atmosphere and ocean and found that a subset of the model's spectrum of eigenmodes resembles the ACW. Through a Fourier analysis of an ensemble of numerical simulations forced by stochastic noise, it can be seen that the forcing must be of low frequency and low wavenumber for the model to generate variability consistent with the observed ACW. Ultimately, the ENSO is most likely the source of such forcing implying that the ACW may be driven ultimately from the Tropics.