Statistics of spatial-temporal variations of sea surface height based on Topex altimeter measurements

A data analysis technique is developed to estimate 3-D spatial-temporal autocorrelation functions and 2-D power spectra of sea surface height (SSH) variations, based on non-gridded Topex/Poseidon altimeter data. The resulting wavenumber spectra are rather anisotropic and characterized by a rapid, nearly power-law-type roll-off at wavenumbers above 0.02 rad km-1 (wavelengths under 300 km) in mid-latitude regions - consistent with the kinetic energy spectra of geostrophic turbulence. The autocorrelation functions contain information on long-wave processes, such as baroclinic Rossby waves. The present statistical approach provides quantitative description of the SSH field variations in a broad range of scales, and it yields an experimental confirmation of baroclinic inertia-gravity wave turbulence.