Tidal Variations in Earth Rotation


Citations for these data:

U Seiler, Periodic changes of the angular momentum budget due to the tides of the world ocean, Journal of Geophysical Research, 96, 10287, 1991.

R S Gross, The effect of ocean tides on the Earth's rotation as predicted by the results of an ocean tide model, Geophysical Research Letters, 20, 293, 1993.


Seiler's model of the ocean tides is a purely numerical model. No tidal observations were used in its solution. Seiler solved Laplace's tidal equations on a global finite-difference grid using time-stepping methods. Dissipation was effected by quadratic bottom drag and a turbulent eddy viscosity.

The Earth-rotation data given here are extracted directly from the above reference by Gross (1993), who computed the data from Seiler's previously published estimates of angular momentum. Amplitude and Greenwich phase lag are given for major tidal constituents, decomposed into parts due to tidal heights and to tidal currents.

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 

                      M2              S2              N2
                    -----           -----           -----
Tidal currents    41.9  221       24.7  248        7.6  230
Tidal heights      8.5    6        7.9   40        0.2  337
TOTAL             35.3  230       18.1  260        7.5  231

                      K1              O1              P1
                    -----           -----           -----
Tidal currents    17.2   53       24.2   24        6.4   55
Tidal heights      1.5   35       11.1   17        0.9   93
TOTAL             18.7   52       35.2   22        7.1   59

                      Mf               Mm
                    -----            -----  
Tidal currents    10.3    7.8     5.4    1.3
Tidal heights     90.8  285.8   106.9  280.7
TOTAL             92.8  292.1   108.0  283.5

 
  
               TIDAL VARIATIONS IN PROGRADE POLAR MOTION 

                      M2              S2              N2
                    -----           -----           -----
Tidal currents    144.   87       46.8   72       29.1   91
Tidal heights      56.  231       16.2  258       16.6  223
TOTAL             105.  105       30.7   68       21.9  126

                      K1              O1              P1
                    -----           -----           -----
Tidal currents     64.   40        42.  223       27.5   49
Tidal heights     120.   82       217.   71       30.2   82
TOTAL             172.   68       181.   78       55.3   67

                      Mf               Mm
                    -----            -----  
Tidal currents    52.7  233        45.6  253
Tidal heights      3.9  263         7.6  264
TOTAL             56.1  235        53.0  254

 
  
             TIDAL VARIATIONS IN RETROGRADE POLAR MOTION 

                      M2              S2              N2
                    -----           -----           -----
Tidal currents    303  226         261  277        32  230
Tidal heights      82  342          53   46        15  294
TOTAL             303  240         232  287        40  249

                      K1              O1              P1
                    -----           -----           -----
Tidal currents     76  274          71  234        37  298
Tidal heights    8910  148          45  142       912  151
TOTAL            8865  148          83  201       881  153

                      Mf               Mm
                    -----            -----  
Tidal currents    31.1   17        34.0  349
Tidal heights     36.7  116        35.8   65
TOTAL             44.0   72        55.0   28