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Note on a simple measure of the Earth's daily magnetic activity
Journal of Geophysical Research
of the De Bilt Observatory, makes a very desirable comparison, chiefly for the year !915, of measures of terrestrial magnetic activity proposed by various investigators. For the various measures, designated below, the following symbols are used here' D, magnetic declination; H, horizontal intensity; Z, vertical intensity; R, absolute diurnal range, ov difference between extreme daily values of element considered; and A, diurnal range of hourly values (mean value over 60-minute interval).doi:10.1029/te027i001p00031 fatcat:epdddmdqinb5vc4us5qyptedsa