Fig. 3From: NOAA/NCEI and University of Colorado candidate models for IGRF-13An example of SV determination at Honolulu (HON). The red lines on the left panels represent the SV spline model with annual differences of filtered observatory data in black. Right panels show the raw data (blue), filtered data (green), and spline fits (red). The circles in the left panel show our predicted SV at 2020.0. The vertical green lines indicate the timestamp of the latest available SV estimate which did not require spline extrapolationBack to article page