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A mechanism for the loading‐unloading substorm cycle missing in MHD global magnetospheric simulation models
Author(s) -
Klimas Alex J.,
Uritsky Vadim M.,
Vassiliadis Dimitris,
Baker Daniel N.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl022916
Subject(s) - substorm , magnetohydrodynamics , physics , mechanics , instability , resistive touchscreen , mechanism (biology) , current sheet , current (fluid) , magnetic reconnection , electric field , field (mathematics) , surge , geophysics , plasma , magnetosphere , meteorology , computer science , computer vision , mathematics , quantum mechanics , pure mathematics , thermodynamics
A 2‐dimensional numerical driven current‐sheet model has been developed that incorporates an idealized current‐driven instability with a resistive MHD system. Under steady loading, the model exhibits a global loading‐unloading cycle. The specific mechanism for producing the loading‐unloading cycle is discussed. It is shown that scale‐free avalanching of electromagnetic energy through the model, from loading to unloading, is carried by repetitive bursts of localized reconnection. Each burst leads, somewhat later, to a field configuration that is capable of exciting a reconnection burst again. This process repeats itself in an intermittent manner while the total field energy in the system falls. The total field energy is reduced to well below that necessary to initiate an unloading event and, thus, a loading‐unloading cycle results. It is shown that, in this model, it is the topology of bursty localized reconnection that is responsible for the appearance of the loading‐unloading cycle.