Open AccessThe change in S q ( H ) amplitude on Abnormal Quiet Days
Author(s) -
Brown G. M.
Publication year - 1986
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1986.tb03838.x
Subject(s) - amplitude , interplanetary magnetic field , earth's magnetic field , geophysics , ionosphere , quiet , solar wind , latitude , physics , geology , magnetic field , geodesy , electric field , atmospheric sciences , astronomy , optics , quantum mechanics
Summary. Analysis of geomagnetic data has shown that the superposed northward magnetic field, which reduces the S q ( H ) amplitude at northern mid‐latitude stations on Abnormal Quiet Days, and increases the amplitude at stations on the equatorward side of the S q focus, builds up in amplitude over four to five days before the AQD occurs, and subsides over a similar period after the AQD. It is inferred indirectly that the azimuthal component B y of the interplanetary magnetic field varies similarly. Data for the opposite meridian show that the imposed field reverses to a southward direction at lower latitudes. The inferred currents to account for these fields are believed to flow in the ionosphere, but to arise from magnetospheric electric fields induced by the solar wind‐transported IMF.