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MHD simulations of the response of high‐latitude potential patterns and polar cap Boundaries to sudden southward turnings of the interplanetary magnetic field
Author(s) -
Lopez R. E.,
Wiltberger M.,
Lyon J. G.,
Goodrich C. C.,
Papadopoulos K.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl900113
Subject(s) - interplanetary magnetic field , noon , convection , polar , geophysics , magnetohydrodynamics , ionosphere , geology , latitude , physics , field line , interplanetary spaceflight , midnight , polar cap , magnetic field , geodesy , atmospheric sciences , mechanics , solar wind , astronomy , quantum mechanics
3‐D MHD simulations were used to investigate the behavior of the high‐latitude convection and the polar cap variations during two events characterized by sudden southward IMF turnings. In agreement with recent observations the simulation results indicate that the convection pattern across the entire polar cap begins to change a few minutes after the arrival of the southward IMF. In contrast, the onset of the equatorward motion of the open closed field‐line boundary depends on the local time, with equatorward motion of the midnight boundary delayed by about 20 minutes relative to the the onset of the boundary motion at noon. We interpret this delay as the time required to convect newly merged flux from the dayside to the nightside. We belive that these two different responses can reconcile apparent contradictions in studies of ionospheric reconfigurations in response to changes in the IMF.