Auroral activity associated with pressure pulses and substorms : A comparison between global fluid modeling and Viking UV imaging

R. M Winglee; J. D Menietti

doi:10.1029/97JA03732

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Auroral activity associated with pressure pulses and substorms : A comparison between global fluid modeling and Viking UV imaging

Journal article

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Auroral activity associated with pressure pulses and substorms : A comparison between global fluid modeling and Viking UV imaging

R. M Winglee and J. D Menietti

Journal of geophysical research, Vol.103(A5), pp.9189-9205

05/01/1998

DOI: 10.1029/97JA03732

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Abstract

Global three-dimensional fluid simulations in conjunction with Viking UV observations are used to investigate the response of the auroral region to solar wind pressure pulses. The fluid simulations differ from ideal MHD in that the steady state electron momentum equation which incorporates the Hall and gradient pressure terms is used instead of the idealized Ohm's law. This treatment produces important corrections to the currents that map into the noon and midnight sectors of the auroral regions and can be important in determining magnetospheric activity during periods of changing interplanetary magnetic field (IMF). Two pressure pulses observed by IMP 8 in the solar wind are shown to produce transient (a few minute) variations in the auroral oval, starting with brightenings near noon which then quickly propagate into the nightside. Of the two pulses, the second pulse which is accompanied by southward IMF produces the larger nightside activity. The model shows that the observed UV brightenings are accompanied by large increases in the auroral field-aligned currents (of the order of 1 MA) at approximately the same MLT as the UV brightenings. However, the current enhancements produced by each pulse are shown to develop along slightly different latitudes of the existing region 1 currents so that the current system can become filamented. The noon currents are also shown to be highly dependent on both By and Bz components of the IMF.

Earth, ocean, space

Exact sciences and technology

External geophysics

Interaction between magnetosphere and interplanetary space

Physics of the magnetosphere

Details

Title: Subtitle: Auroral activity associated with pressure pulses and substorms : A comparison between global fluid modeling and Viking UV imaging
Creators: R. M Winglee - University of Washington
J. D Menietti - University of Iowa
Resource Type: Journal article
Publication Details: Journal of geophysical research, Vol.103(A5), pp.9189-9205
Publisher: American Geophysical Union
DOI: 10.1029/97JA03732
ISSN: 0148-0227
eISSN: 2156-2202
Language: English
Date published: 05/01/1998
Academic Unit: Physics and Astronomy
Record Identifier: 9984627183802771

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