Fig. 3. Climate-induced polar motion.

(A) Polar motion excitations caused by four climate-related sources. (B) Total reconstructed (REC) and observed (OBS) excitations. We add global (nontidal) AOM-associated excitations (${\stackrel{.}{\mathrm{\chi }}}_1=-0.03$ and ${\stackrel{.}{\mathrm{\chi }}}_2=0.22$ mas/year) to the reconstructed solutions and remove the 20th century linear trends from the observations (see Materials and Methods). (For ease of comparison, minor smoothing is applied to the observed data.) Large positive gradients during 2005–2012 (cyan shadow), followed by negative trends, are apparent for χ₂(t), and it may be explained by analogous trends associated with TWS [see (A)].