Fig. 6From: COV-OBS.x2: 180 years of geomagnetic field evolution from ground-based and satellite observationsIn black: MF (left) and SV (right) Lowes spectra (Eq. (3)) of our estimate of the unmodeled internal field at high frequencies due to the projection onto splines 2 years apart. It is constructed from the residuals to a spline fit to synthetic AR-2 series (see text for details). In color (dotted lines) are shown the spectra for the COV-OBS.x2 formal posterior uncertainty at epochs 1855, 1895, 1935, 1975, and 2015. These latter are obtained from the \(\pm \sigma \) spread within an ensemble of COV-OBS.x2 realizations (i.e., projected onto splines)Back to article page