THE GLOBAL FREQUENCY-WAVE-NUMBER SPECTRUM OF OCEANIC VARIABILITY ESTIMATED FROM TOPEX POSEIDON ALTIMETRIC MEASUREMENTS/

Two years of altimetric data from the TOPEX/POSEIDON spacecraft have b een used to produce preliminary estimates of the space and time spectr a of global variability for both sea surface height and slope. The res ults are expressed in terms of both degree variances from spherical ha rmonic expansions and in along-track wavenumbers. Simple analytic appr oximations both in terms of piece-wise power laws and Pade fractions a re provided for comparison with independent measurements and for easy use of the results. A number of uses of such spectra exist, including the possibility of combining the altimetric data with other observatio ns, predictions of spatial coherences, and the estimation of the accur acy of apparent secular trends in sea level.