= Soop =
=== Handbook of Geostationary Orbits ===
=== E. M. Soop, 1983 ===

East-west acceleration, extrapolated from table 2, pp 287 

|| λ  degrees || acceleration ||<:> λ change || ΔV per year ||<:> Δλ      ||
|| Longitude  || × 1e-9 m/s²  || 0.001°/day² ||<:> m/s/y    ||<:> °/year² ||
||<)>     0 W ||<)> 21.3 W ||<)> 0.65 W ||<)> 0.67 W ||<)>  87 W ||
||<)>    15 W ||<)>  6.3 E ||<)> 0.19 E ||<)> 0.20 E ||<)>  25 W ||
||<)>    30 W ||<)> 29.6 E ||<)> 0.90 E ||<)> 0.97 E ||<)> 120 E ||
||<)>    45 W ||<)> 43.5 E ||<)> 1.33 E ||<)> 1.38 E ||<)> 177 E ||
||<)>    60 W ||<)> 46.5 E ||<)> 1.42 E ||<)> 1.47 E ||<)> 189 E ||
||<)>    75 W ||<)> 38.7 E ||<)> 1.18 E ||<)> 1.22 E ||<)> 157 E ||
||<)>    90 W ||<)> 22.3 E ||<)> 0.68 E ||<)> 0.71 E ||<)>  91 E ||
||<)>   105 W ||<)>  0.3 E ||<)> 0.01 E ||<)> 0.01 E ||<)>   1 E ||
||<)>   120 W ||<)> 23.3 W ||<)> 0.71 W ||<)> 0.73 W ||<)>  95 W ||
||<)>   135 W ||<)> 43.0 W ||<)> 1.31 W ||<)> 1.36 W ||<)> 175 W ||
||<)>   150 W ||<)> 54.4 W ||<)> 1.63 W ||<)> 1.69 W ||<)> 217 W ||
||<)>   165 W ||<)> 50.8 W ||<)> 1.55 W ||<)> 1.60 W ||<)> 207 W ||
||<)>   180 W ||<)> 34.2 W ||<)> 1.04 W ||<)> 1.08 W ||<)> 139 W ||
||<)>   165 E ||<)>  6.6 W ||<)> 0.02 W ||<)> 0.21 W ||<)>   3 W ||
||<)>   150 E ||<)> 25.3 E ||<)> 0.77 E ||<)> 0.80 E ||<)> 103 E ||
||<)>   135 E ||<)> 52.3 E ||<)> 1.59 E ||<)> 1.65 E ||<)> 212 E ||
||<)>   120 E ||<)> 65.3 E ||<)> 1.99 E ||<)> 2.06 E ||<)> 265 E ||
||<)>   105 E ||<)> 58.9 E ||<)> 1.79 E ||<)> 1.86 E ||<)> 239 E ||
||<)>    90 E ||<)> 34.5 E ||<)> 1.05 E ||<)> 1.09 E ||<)> 140 E ||
||<)>    75 E ||<)>  0.0 W ||<)>  0.0 W ||<)>  0.0 W ||<)> 0.0 W ||
||<)>    60 E ||<)> 33.0 W ||<)> 1.01 W ||<)> 1.04 W ||<)> 135 W ||
||<)>    45 E ||<)> 54.3 W ||<)> 1.65 W ||<)> 1.71 W ||<)> 220 W ||
||<)>    30 E ||<)> 58.3 W ||<)> 1.77 W ||<)> 1.84 W ||<)> 236 W ||
||<)>    15 E ||<)> 45.5 W ||<)> 1.38 W ||<)> 1.44 W ||<)> 184 W ||

NOTE: large Δλ isn't "real", but implies a large oscillation and reversal.  The oscillation is not sinusoidal, because the "restoring force" isn't linear with distance from "center"

The above table is for east/west oscillations due to the Earth's sideways bulges at 75E and 105W, in the absence of tidal forces from the Moon and the Sun.  There will also be large accelerations east/west and north/south from lunar and solar tides.  As a wild guess, whatever vertical effect that tides have on the ocean will be magnified some power of the GEO radius in earth radius units (6.61)