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Title: Substorm features in MHD (magnetohydrodynamics) simulations of magnetotail dynamics

Abstract

We present a review and extended analysis of characteristic results from our nonideal three-dimensional MHD simulations of unstable magnetotail evolution, which develops without the necessity of external driving or prescribed localization on nonideal effects. These modes involve magnetic reconnection at a near-Earth site in the tail, consistent with the near-Earth neutral line model of substorms. The evolution tailward of the reconnection site is characterized by plasmoid formation and ejection into the far tail, plasma sheet thinning between the near-Earth neutral line (X line) and the departing plasmoid, and fast tailward flow, which occupies large sections of the plasma sheet at larger distance from the X line, while it occurs only in very limited space and time sections close to the X line. The region earthward of the X line is characterized by dipolarization, propagating from midnight toward the flank regions and, perhaps, tailward. It is associated with the signatures of the substorm current wedge: reduction and diversion of cross-tail current from a region surrounding the reconnection site and increase of Region 1 type field-aligned currents. A mapping of these currents to the Earth on the basis of an empirical magnetic field model shows good agreement of the mapped current systemmore » with the observed Region 1 field-aligned current system and its substorm associated changes, including also a nightward and equatorward shift of the peaks of the field-aligned current density. The evolution of the mappings of the boundaries of the closed field line region bears strong resemblance to the formation and expansion of he auroral bulge. The consistency of all of these details with observed substorm features strongly supports the idea that substorm evolution in the tail is that of a large scale nonideal instability.« less

Authors:
;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (USA)
Sponsoring Org.:
DOE/ER
OSTI Identifier:
6222934
Report Number(s):
LA-UR-91-220; CONF-9009109-2
ON: DE91007407
DOE Contract Number:  
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Chapman conference on magnetospheric substorms, Hakone (Japan), 3-7 Sep 1990
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; MAGNETOTAIL; MAGNETOHYDRODYNAMICS; BOUNDARY CONDITIONS; MAGNETIC FIELDS; MAPPING; PLASMA SIMULATION; PLASMOIDS; EARTH ATMOSPHERE; EARTH MAGNETOSPHERE; FLUID MECHANICS; HYDRODYNAMICS; MECHANICS; SIMULATION; 640201* - Atmospheric Physics- Auroral, Ionospheric, & Magetospheric Phenomena

Citation Formats

Birn, J, and Hesse, M. Substorm features in MHD (magnetohydrodynamics) simulations of magnetotail dynamics. United States: N. p., 1990. Web.
Birn, J, & Hesse, M. Substorm features in MHD (magnetohydrodynamics) simulations of magnetotail dynamics. United States.
Birn, J, and Hesse, M. 1990. "Substorm features in MHD (magnetohydrodynamics) simulations of magnetotail dynamics". United States. https://www.osti.gov/servlets/purl/6222934.
@article{osti_6222934,
title = {Substorm features in MHD (magnetohydrodynamics) simulations of magnetotail dynamics},
author = {Birn, J and Hesse, M},
abstractNote = {We present a review and extended analysis of characteristic results from our nonideal three-dimensional MHD simulations of unstable magnetotail evolution, which develops without the necessity of external driving or prescribed localization on nonideal effects. These modes involve magnetic reconnection at a near-Earth site in the tail, consistent with the near-Earth neutral line model of substorms. The evolution tailward of the reconnection site is characterized by plasmoid formation and ejection into the far tail, plasma sheet thinning between the near-Earth neutral line (X line) and the departing plasmoid, and fast tailward flow, which occupies large sections of the plasma sheet at larger distance from the X line, while it occurs only in very limited space and time sections close to the X line. The region earthward of the X line is characterized by dipolarization, propagating from midnight toward the flank regions and, perhaps, tailward. It is associated with the signatures of the substorm current wedge: reduction and diversion of cross-tail current from a region surrounding the reconnection site and increase of Region 1 type field-aligned currents. A mapping of these currents to the Earth on the basis of an empirical magnetic field model shows good agreement of the mapped current system with the observed Region 1 field-aligned current system and its substorm associated changes, including also a nightward and equatorward shift of the peaks of the field-aligned current density. The evolution of the mappings of the boundaries of the closed field line region bears strong resemblance to the formation and expansion of he auroral bulge. The consistency of all of these details with observed substorm features strongly supports the idea that substorm evolution in the tail is that of a large scale nonideal instability.},
doi = {},
url = {https://www.osti.gov/biblio/6222934}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1990},
month = {1}
}

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