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Simultaneous observations of the auroral ovals in both hemispheres under varying conditions
Author(s) -
Stubbs T. J.,
Vondrak R. R.,
Østgaard N.,
Sigwarth J. B.,
Frank L. A.
Publication year - 2005
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 - 10.1029/2004gl021199
Subject(s) - noon , asymmetry , meridian (astronomy) , geology , northern hemisphere , interplanetary magnetic field , polar cap , geodesy , magnetosphere , physics , southern hemisphere , polar , dusk , geophysics , astrophysics , solar wind , atmospheric sciences , climatology , ionosphere , astronomy , magnetic field , quantum mechanics
This is the first analysis to use simultaneous observations of the entire auroral ovals in both hemispheres to track their location. Data was used from the Polar VIS and IMAGE FUV imagers on 23 October 2002 and plotted in AACGM coordinates. Results showed the expected IMF B y ‐dependent asymmetry along the dawn‐dusk meridian; however, there was an unexpected offset of both ovals toward dawn. Evidence is also shown for an asymmetry along the noon‐midnight meridian dependent on both dipole tilt angle and the sense of IMF B x . During a brief period of weak IMF B z > 0 and IMF B x > 0, the southern oval is observed to move equatorward relative to the northern oval, consistent with tail lobe reconnection occurring only in the southern hemisphere. This has important implications for the global response of the magnetosphere to different interplanetary conditions.