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Magnetosphere‐Ionosphere Convection Under the Due Northward IMF
Author(s) -
Tanaka T.,
Obara T.,
Watanabe M.,
Fujita S.,
Ebihara Y.,
Kataoka R.,
Den M.
Publication year - 2019
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2019ja026547
Subject(s) - magnetosphere , plasma sheet , physics , geophysics , ionosphere , interplanetary magnetic field , convection , magnetopause , plasma , current sheet , field line , magnetic reconnection , solar wind , mechanics , magnetohydrodynamics , quantum mechanics
Convection under the due northward interplanetary magnetic field (IMF) is reproduced by the global simulation. The resulting magnetosphere is closed except in the XZ plane and separated from the solar wind by the separatrix generated from cusp nulls. Inside the separatrix, there exist three plasma regimes of the cusp high‐pressure region, the low‐latitude boundary layer (LLBL) and the plasma sheet. In the ionosphere, the northward Bz (NBZ) current and the reverse cell occur in higher latitudes than 80°, and the fun‐shaped arc‐like field‐aligned current and the main oval occur in lower latitudes than 80°. Magnetic field lines in the antisunward flow region of the reverse cell are connected to the LLBL that is accelerated to supersonic flow by the cusp pressure. Circulation on the reverse cell in the ionosphere is as a whole constructed to the interchange cycle in the magnetosphere. Convection is looked upon as the process to discharge stress generated by the dayside cusp reconnection. Magnetic stress generated by the reconnection is first converted to thermal energy in the cusp. This thermal energy is drained through three possible routes: release of plasma downtail through the LLBL, dissipation as electromagnetic energy through formation of the dynamo, and evacuation down to the ionosphere through the plasma sheet.