The table below contains the parameters of the ITRF2020 seasonal geocenter
motion model. The sign and phase conventions used are such that the seasonal
motion of the Earth's center of figure (CF) with respect to the Earth's center
of mass (CM), along any X, Y, Z axis, is obtained by:
    A1 * cos(2*pi*t - pi/180*phi1) + A2 * cos(4*pi*t - pi/180*phi2)
where:
  - A1 is the annual amplitude from the table below,
  - phi1 if the annual phase from the table below,
  - A2 is the semi-annual amplitude from the table below,
  - phi2 if the semi-annual phase from the table below,
  - t is the time in decimal years.

               Amplitude (mm)   Phase (Degrees)
-----------------------------------------------
annual      X  1.23 +/- 0.16   -123.2 +/-   7.2
annual      Y  3.48 +/- 0.15    152.9 +/-   2.5
annual      Z  2.76 +/- 0.33   -139.5 +/-   6.8

Semi-annual X  0.49 +/- 0.15    107.2 +/-  18.1
Semi-annual Y  0.22 +/- 0.15      1.6 +/-  39.0
Semi-annual Z  1.19 +/- 0.33     30.5 +/-  15.5