Fig. 1: Polar motion observations.
From: Contributions of core, mantle and climatological processes to Earth’s polar motion
a, Polar motion (1900–2018) from the IERS C01 series in units of mas. b, The long-period polar motion (solid lines) and their uncertainties at the one standard deviation level (shaded envelope, that is, mean signal ± their uncertainties) after the removal of all periods shorter than 500 days. In both a and b, the reference (xp = yp = 0) is chosen as the mean position in the interval 2002–2018 (shaded grey area). c, Polar view of the long-period polar motion relative to 1900. xp is positive towards Greenwich (0°); yp is positive towards 90° W. An angular motion of 1 mas corresponds to a displacement of 3.09 cm at Earth’s surface.
