James Girton (University of Washington, USA); Matthew Alford (Scripps Institution of Oceanography, USA)

Global maps of mode-1 M2, S2, O1 and K1 internal tides are constructed using the sea surface height measurements by multiple satellites including ERS-2, Envisat, TOPEX/Poseidon (T/P), Jason-1/2, and Geosat Follow-On (GFO). A plane-wave fit method is employed to extract multiple internal tides in arbitrary horizontal directions. The fitting procedure has been refined to (1) suppress aliasing signals from eddies, (2) evaluate 95% confidence levels, and (3) optimize the number of output waves based on background noise level. Our results, including amplitude and phase, may work as a prototypical empirical internal tide model.

Complicated interference patterns formed by multiple internal tides mask individual internal tidal beams. To better study regional internal tides, internal tidal beams originating from several strong generation sites are resolved and investigated. The phase speeds inferred from the along-beam propagation agree with the theoretical values very well. The M2 internal tides around the Hawaiian Ridge from satellites and numerical models are compared. Some issues with this technique are discussed for future improvements.