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Table 2

Linear correlation coefficients between mid-latitude range indices and the SuperMAG and auroral electrojet indices: r and r* are for 3-hourly values and the 8-point running means, respectively. The data used are for 1996–2017 (inclusive). This yields 61368 3-hourly samples (am, ap and aa) and 6136124 running-mean samples (Am*, Ap* and Aa*). For all correlations, the large number of samples ensures that the correlation significance level, derived by comparison with the AR1 red noise model, is 100% to within at least three decimal places for all cases. The maximum SME and minimum SML in each 3-hour intervals is SMEmax and SMLmin respectively.

Interval (h) am ap aa
SMEmax 3 r 0.840 0.806 0.832
SME τ=3h 3 r 0.784 0.741 0.772
AEmax 3 r 0.824 0.767 0.815
AE τ=3h 3 r 0.784 0.741 0.772
SMLmin 3 r −0.823 −0.777 −0.807
SML τ=3h 3 r −0.792 −0.748 −0.779
ALmin 3 r −0.822 −0.766 −0.810
AL τ=3h 3 r −0.792 −0.748 −0.779

Am* Ap* Aa*

SMEmax* 24 r* 0.908 0.881 0.913
SME τ=24h 24 r* 0.866 0.826 0.864
AEmax* 24 r* 0.891 0.853 0.901
AE τ=24h 24 r* 0.856 0.826 0.864
SMLmin* 24 r* −0.890 −0.867 −0.867
SML τ=24h 24 r* −0.848 −0.847 −0.848
ALmin* 24 r* −0.900 −0.865 −0.865
AL τ=24h 24 r* −0.875 −0.847 −0.848

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