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Multi-Scale Modeling of Magnetospheric ReconnectionOne of the major challenges in modeling the magnetospheric magnetic reconnection is to quantify the interaction between large-scale global magnetospheric dynamics and microphysical processes in diffusion regions near reconnection sites. There is still considerable debate as to what degree microphysical processes on kinetic scales affect the global evolution and how important it is to substitute numerical dissipation and/or ad hoc anomalous resistivity by a physically motivated model of dissipation. Comparative studies of magnetic reconnection in small scale geometries demonstrated that MHD simulations that included non-ideal processes in terms of a resistive term $\eta J$ did not produce the fast reconnection rates observed in kinetic simulations. For a broad range of physical parameters in collisionless magnetospheric plasma, the primary mechanism controlling the dissipation in the vicinity of the reconnection site is non-gyrotropic effects with spatial scales comparable with the particle Larmor radius. We utilize the global MHD code BATSRUS and incorporate nongyrotropic effects in diffusion regions in terms of corrections to the induction equation. We developed an algorithm to search for magnetotail reconnection sites, specifically where the magnetic field components perpendicular to the local current direction approaches zero and form an X-type configuration. Spatial scales of the diffusion region and magnitude of the reconnection electric field are calculated selfconsistently using MHD plasma and field parameters in the vicinity of the reconnection site. The location of the reconnection sites is updated during the simulations. To clarify the role of nongyrotropic effects in diffusion region on the global magnetospheric dynamic we perform simulations with steady southward IMF driving of the magnetosphere. Ideal MHD simulations with magnetic reconnection supported by numerical resistivity produce steady configuration with almost stationary near-earth neutral line (NENL). Simulations with non-gyrotropic corrections demonstrate dynamic quasi-periodic response to the steady driving condition. The loading/unloading cycle in non-gyrotropic MHD results has a non-stationary reconnection site in the magnetotail, with the retreating during the stretching phase and then a new NENL forming in the resulting thin plasma sheet. We expect that this model will lead to improved representations of space weather event in the magnetosphere.
Document ID
20070016000
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Kuznetsova, M. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hesse, M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Rastatter, L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Toth, G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dezeeuw, D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Gomobosi, T.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2007
Subject Category
Geosciences (General)
Meeting Information
Meeting: 2006 GEM Workshop
Location: Snowmass, CO
Country: United States
Start Date: June 24, 2006
End Date: June 30, 2006
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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