The Oceanic Variability Spectrum and Transport Trends

Oceanic meridional transports evaluated over the width of the Pacific Ocean from altimetric observations become incoherent surprisingly rapidly with meridional separation. Even with 15 years of data, surface slopes show no significant coherence beyond 5 of latitude separation at any frequency. An analysis of the frequency/zonal-wavenumber spectral density shows a broad continuum of motions at all time and space scales, with significant excess energy along a 'non-dispersive' line extending from the barotropic to the first baroclinic mode Rossby waves. It is speculated that much of that excess energy lies with coupled barotropic and first mode Rossby waves. The statistical significance of apparent oceanic transport trends depends upon the existence of a reliable frequency/wavenumber spectrum for which only a few observational elements currently exist.