Rossby Waves in the Southern Ocean: A comparison of TOPEX/POSEIDON altimetry with model predictions

Results are presented from an eddy-resolving model of the Southern Ocean which suggest that regions of moderate eddy activity are occupied by wavelike eddies with wavelengths of about 300 km and periods of 4 to 12 months. These waves travel eastward where the current (and wave amplitude)is strongest, and westward elsewhere, and it is argued that they are Rossby waves advected by the mean flow. It is shown that TOPEX/POSEIDON altimetry data should be able to resolve these waves in the Pacific sector of the Southern Ocean. A technique for wave detection is then presented which is capable of extracting useful information about the waves in this as well as other regions. Altimeter data are then presented which confirm the existence of waves in the Pacific sector and are consistent with wave presence elsewhere. An analysis of tide model errors shows that such errors are incapable of producing a signal which could mimic the modeled waves, although tide model errors may explain the difference between altimetry and model results in shallow regions of the ocean and in regions of low eddy activity.