A new model for auroral breakup during substorms
A model for substorm breakup is developed, based on the relaxation of stretched (closed) dipolar field lines, and the formation of an incipient current wedge within a single arc structure. It is argued that the establishment of a coupled current structure within a single arc leads to a quasi-stable system; i.e., the pre-breakup regime. Perturbation of the pre-breakup structure leads to an instability criterion. It is found, consistent with observations, that narrower auroral arcs at lower L shells undergo the most explosive poleward expansion. According to this model, the precise location at which breakup occurs depends on the O/sup +/ density in the plasma sheet, the level of magnetic activity (K/sub p/), and the intensity of the substorm westward electrojet in the ionosphere. An enhancement of any of these features will cause breakup to occur at lower L shells. Comparison of our model with the Heppner-Maynard polar-cap potential model indicates that breakup is restricted to the west of the Harang discontinuity consistent with recent observations from the Viking satellite.
- Research Organization:
- Air Force Geophysics Lab., Hanscom Air Force Base, Bedford, MA (US); Dept. of Plasma Physics, Royal Institute of Technology, S100 44 Stockholm 70 (SE); Center for Electromagnetics Research, Northeastern Univ., Boston, MA (US)
- OSTI ID:
- 6131723
- Journal Information:
- IEEE Trans. Plasma Sci.; (United States), Vol. 17:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AURORAE
IONOSPHERE
ELECTROJETS
HARANG DISCONTINUITY
INSTABILITY
L SHELL
MAGNETIC STORMS
PLASMA EXPANSION
PLASMA SHEET
PLASMA SIMULATION
RELAXATION
AURORAL OVAL
CURRENTS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
ELECTRONIC STRUCTURE
EXPANSION
PLANETARY IONOSPHERES
SIMULATION
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena
700107 - Fusion Energy- Plasma Research- Instabilities