Open Access
Research Article

Fig. 6


Download original image

Top: Scaled variations of modern a K values from various stations using the station location correction procedure used in this paper. For all stations, the observed a K values have been corrected for any secular magnetic field change by dividing by the s(δ) factor and then scaled to the am index using the linear regression coefficients m and i obtained from the calibration interval (2002–2009, inclusive). The plot shows 27-day Bartels rotation means for data from: (mauve) Sodankylä, SOD; (brown) Eskdalemuir, ESK; (orange) Niemegk, NGK; (red) Hartland, HAD; (blue) Canberra, CNB; and (green) a spline of Gangara, GNA and nearby Gingin, GNG (see text for details). The black line is the am index. Bottom: the rms. fit residual of the re-scaled station a K indices compared with the am index, ε rms, for the 27-day means. The average of ε rms for the whole interval shown (1995–2017), is 〈ε rms〉 = 9.7%

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.