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Characteristics of Reconnection Sites and Fast Flow Channels in an MHD Simulation
Author(s) -
McPherron R. L.,
ElAlaoui M.,
Walker R. J.,
Richard R.
Publication year - 2020
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2019ja027701
Subject(s) - magnetohydrodynamics , physics , magnetic reconnection , phase (matter) , ionosphere , flux (metallurgy) , line (geometry) , flow (mathematics) , quiet , computer simulation , geophysics , astrophysics , computational physics , mechanics , magnetic field , geometry , astronomy , materials science , mathematics , quantum mechanics , metallurgy
We investigate an interval of moderate magnetic activity from 0–8 UT on 14 March 2008 by using a global magnetohydrodynamics (MHD) simulation with high spatial and temporal resolution. Observations show several distinct substorms during this interval. One of these with onset at 04:44 UT occurs at 04:42 UT in the simulation. The simulation shows reconnection is continuously present at multiple sites. During the growth phase, the number of X‐lines decreases as their total length increase and their locations approach the Earth. The X‐lines create multiple fast flow channels with dipolarization fronts. The total length and area of these channels increase during the growth phase as they penetrate closer to the Earth carrying more magnetic flux. The 04:42 UT onset in the simulation was preceded by the growth of an X‐line that eventually extended 55 R E from 12 R E premidnight to 50 on the dawn side. It produced a narrow flow channel parallel to the X‐line that eventually penetrated inside 10 R E rapidly depositing magnetic flux as the expansion phase developed. Despite this good agreement in expansion phase onset time, ground and satellite observations suggest a quiet growth phase with a sudden onset of reconnection. It may be possible to explain the difference between observations and simulations if all growth phase activity in the simulation maps to the ionosphere at very high latitudes. An auroral streamer at onset maps in the simulation very close to Earth. A recovery phase streamer maps to the middle tail.