Fig. 2.

(A) Radial distance of the eccentric dipole from the rotation axis (s_c) based on 1,000 samples from the pfm9k.2 posterior distribution (semitransparent black lines) and the posterior mean (thick black line). Also shown is the posterior mean contribution from Gauss coefficients $g_2^1$ and $h_2^1$ (dashed red line, upper x axis). (B) Time–longitude density plot of the eccentric dipole locations projected onto the equatorial plane (i.e., ignoring the z component) based on 1,000 posterior samples. Horizontal dotted black lines are added to illustrate the identified ∼1,300-y quasiperiodic variations in both the DM and the eccentric dipole location. (C) The eccentric dipole locations projected onto the equatorial plane based on 1,000 posterior samples (every 50 y) and the posterior mean model (black line), both over the period 7000 BCE to 1850 CE. The eccentric dipole determined from COV-OBS.x2 for years 1840 to 2000 CE (blue line) is shown for reference. Red and green stars mark the locations of the eccentric dipole at 2020 CE and 600 BCE, respectively.