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Magnetic activity in the polar cap—A new index

1988; Elsevier BV; Volume: 36; Issue: 11 Linguagem: Inglês

10.1016/0032-0633(88)90063-3

1873-5088

О. А. Troshichev, V. G. Andrezen, S. Vennerstrøm, E. Friis‐Christensen,

Geophysics and Gravity Measurements

A magnetic activity index PC measuring DP2 magnetic perturbations in the central polar cap is derived, and its relationship to various solar wind parameters is investigated through a linear correlation analysis. The PC index is based on data from a single nearpole station, and the index values derived from a station near the south pole, Vostok, are compared with simultaneous index values derived from a station near the north pole, Thule. It is concluded that the index shows a good correlation with the southward component of the interplanetary magnetic field IMF or, even better, the solar wind parameters vBzorvBt sin2θ2. In the derivation of the index the following items are taken into account: (1) seasonal changes, (2) inhomogeneity in magnitude and direction of the magnetic perturbation in the nearpole region and (3) a time delay between variations in the solar wind parameters and the subsequent response in the polar cap.