The global power of the differences of altimetric sea heights at collo
cated points in the first 44 cycles of the Topex/Poseidon (T/P) missio
n, apparently shows the influence of errors in the major tides and lon
g period ocean signals. Results show the principal semidiurnal tides (
M2/S2 lumped together) in the Cartwright and Ray (1991) model are prob
ably in error globally by 3-4 cm (rms). The dominant fluctuation in th
e differences over the 44 cycles (14 months total) arises from an annu
al signal of 4-6 cm (rms), significantly greater than long term climat
e data suggests (but with considerable uncertainty due to unresolved s
emiannual effects).