Open AccessPolar cap electric field saturation during interplanetary magnetic field B z north and south conditions
Author(s) -
Wilder F. D.,
Clauer C. R.,
Baker J. B. H.
Publication year - 2010
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2010ja015487
Subject(s) - interplanetary magnetic field , geophysics , electric field , interplanetary spaceflight , polar , solar wind , convection , geology , physics , saturation (graph theory) , polar cap , magnetic field , atmospheric sciences , ionosphere , meteorology , astronomy , mathematics , quantum mechanics , combinatorics
We report the results of an investigation of the saturation of the polar cap electric field during periods of large northward and southward interplanetary magnetic field (IMF). While it has been demonstrated that saturation can occur for both northward and southward IMF, a direct comparison between the two regimes during saturated driving has not been performed. We use solar wind measurements to search for events between 1998 and 2007 when the IMF is stable for 50 min. The selected intervals are binned according to interplanetary electric field (− V SW × B ). SuperDARN Doppler radar velocity vectors from high‐latitude antisunward looking beams are averaged to determine the approximate polar cap electric field. Results show that sunward convection under northward IMF is stronger in summer than in winter, but that antisunward convection under southward IMF exhibits the opposite seasonal behavior. One explanation is that, as the earth tilts near solstice, lobe reconnection is less effective in the winter hemisphere.