Dominant propagating signals in sea level anomalies in the Southern Ocean

Abstract

We examine the time evolution over an 11 yr time series of the dominant modes of variability in sea level anomalies (SLA) from TOPEX/Poseidon and ERS‐1/2 in the Southern Ocean (35–60°S). We use Hayashi's classical space‐time spectral analysis and a newly developed method combining a Gabor analysis with Hayashi's method. Zonal wavenumbers 3 and 2 emerge unambiguously with null corresponding meridional wavenumber meaning that both associated modes have no meridional propagation. Their power spectrum density (PSD) is maximum within 50–55°S. The 3/0 mode displays a clear westward propagation associated with a 1.04 yr period. The 2/0 pair is characterized by a ∼4.4 yr period and exhibits a clear eastward propagation with a maximal PSD just after the 1998 El Niño peak. Zonal wavenumber‐2 mode is then probably part of the Antarctic Circumpolar Wave.