GLOBAL CHARACTERISTICS OF OCEAN VARIABILITY ESTIMATED FROM REGIONAL TOPEX POSEIDON ALTIMETER MEASUREMENTS/

Three years of altimetric data from the TOPEX/POSEIDON spacecraft have been used to study characteristics of eddy variability over the World Ocean. The nature of the Variability and its spatial structure are ch aracterized in terms of the geographical distribution of eddy energy, as simple approximations of observed regional frequency and wavenumber spectra, and in terms of associated eddy time and space scares of sea surface height (SSH) variability and geostrophic velocity. Emphasis i s put on summarizing characteristics typical for dynamically distinct regions of the World Ocean. This effort results in an attempt to descr ibe the observed ocean variability in terms of universal spectral rela tions that depend only on few mean flow parameters such as the first-m ode Rossby radius of deformation. Regional peculiarities follow natura lly as deviations from the fundamental frequency and wavenumber spectr a presented here. Frequency spectra of both variables can be summarize d by three basic types representing (i) the energetic boundary current s, (ii) the bulk of the extratropical basins, and (iii) the tropical i nterior oceans. Extratropical wavenumber spectra suggest a geostrophic ally turbulent ocean. They are basically uniform in shape and show a p lateau on long wavelength for SSH and a steep spectral decay close to k(-5) toward smaller wavelengths. The transition between both regimes shifts toward longer cutoff wavenumbers from low to high latitudes, an d related spatial eddy scales can be described in terms of the first-m ode Rossby deformation radius of the mean Row held. Although consisten t with estimated Rhines scales in low latitudes, inferred eddy scales are up to a factor of 0.3 smaller at high latitudes.