B F Chao, R D Ray, J M Gipson, G D Egbert, C Ma, Diurnal/semidiurnal polar motion excited by oceanic tidal angular momentum, J. Geophys. Res., 101, 20151-63, 1996.
G D Egbert, A F Bennett, M G G Foreman, Topex/Poseidon tides estimated using a global inverse model, J. Geophys. Res., 99, 24821-52, 1994.
These harmonic constants for tidal variations in rotation rate and polar motion stem primarily from the TPXO.2 model of Egbert et al. (1994). The data were supplemented in the polar seas by a regional tide model, and the EOP effects were computed and published as ``Model C'' by Chao et al. (1996). The Chao et al. paper is the proper citation for these EOP data, although this web site gives additional details, such as decomposing the harmonic constants into parts due to currents and heights.
Egbert's TPXO.2 model is an assimilation model; it uses both a hydrodynamic model and tidal observations in the form of sea-surface height differences at the cross-over points of the Topex/Poseidon satellite. The tidal heights of this model were tested (along with many other models) by Shum et al. (Journal of Geophysical Research, 102, 25173, 1997), and the tidal currents were tested against acoustic observations by Dushaw et al. ( Progress in Oceanography, 40, 377, 1997).
Each pair of numbers below is an amplitude and a phase lag. Amplitude units for UT are microseconds. Amplitude units for polar motion are microarcseconds. Phase units are degrees.
TIDAL VARIATIONS IN UT1
Q1 O1 P1 K1
----- ----- ----- -----
Tidal currents 3.9 16 16.4 29 6.3 35 19.9 35
Tidal heights 1.9 46 4.6 67 0.7 270 2.9 296
TOTAL 5.6 26 20.1 37 5.9 29 19.7 26
N2 M2 S2 K2
----- ----- ----- -----
Tidal currents 4.2 236 20.5 229 9.6 254 2.7 246
Tidal heights 0.9 339 6.5 352 2.7 37 0.9 36
TOTAL 4.1 248 17.7 246 7.6 267 2.0 259
TIDAL VARIATIONS IN PROGRADE POLAR MOTION
Q1 O1 P1 K1
----- ----- ----- -----
Tidal currents 1.7 148 35.4 98 19.0 94 60.6 100
Tidal heights 27.0 74 112.3 61 41.2 50 127.8 47
TOTAL 27.5 77 142.1 70 56.3 63 171.4 63
N2 M2 S2 K2
----- ----- ----- -----
Tidal currents 14.2 107 80.7 104 46.4 77 11.7 86
Tidal heights 8.2 192 17.4 220 18.1 243 4.9 252
TOTAL 17.0 135 74.6 116 29.2 86 7.0 96
TIDAL VARIATIONS IN RETROGRADE POLAR MOTION
Q1 O1 P1 K1
----- ----- ----- -----
Tidal currents 34.5 302 168.9 302 72 286 197 283
Tidal heights 12.6 318 38.7 139 861 133 9845 132
TOTAL 46.8 306 132.4 297 797 136 9673 133
N2 M2 S2 K2
----- ----- ----- -----
Tidal currents 45.2 249 301.9 257 161.2 290 41.8 293
Tidal heights 15.5 349 78.9 23 35.5 82 9.2 83
TOTAL 45.2 269 262.6 271 130.9 298 34.2 301