Figure 1

Composite paleomagnetic power spectral density (PSD) for the axial dipole term \({g_{1}^{0}}\) estimated from reconstructions on various timescales.gufm1: 1590 to 1990 AD (Jackson et al. 2000); 3 ka models CALS3k.3 and ARCH3k.1 (Korte et al. 2009); pfm9k.1a: a 9 ka model (Nilsson et al. 2014); CALS10k.1b: a 10 ka model (Korte et al. 2011); and PADM2M spanning 2 Ma (Ziegler et al. 2011). Note the absence of spectral estimates bridging frequencies from 30 to 1000 My ⁻¹, outlined by the dashed line.