The geoid spectrum from altimetry

Satellite altimetry information from the world's major oceans has been analyzed to arrive at a geoid power spectrum. Using the equivalent of about 7 revolutions of data (mostly from Geos 3) the power spectrum of the sea surface generally follows the expected values from Kaula's rule applied to the geoid. Analysis of overlapping altimetry arcs (and oceanographic data) shows that the surface spectrum is dominated by the geoid to about 500 cycles (40km half wavelength) but that sea state departures are significant starting at about 250 cycles (80km). Estimates of geopotential variances from a derived (smooth) geoid spectrum show significantly less power than Kaula's rule to about 60 cycles but somewhat more from there to about 400 cycles. At less than 40km half wavelength the total power in the marine geoid may be negligible (≪20cm).