Magnetosphere–Ionosphere Convection as a Compound System |
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Authors: | T Tanaka |
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Institution: | (1) Faculty of Earth and Planetary Sciences, Graduated School of Sciences, Kyushu University, Fukuoka 812-8581, Japan;(2) CREST, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan |
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Abstract: | Convection is the most fundamental process in understanding the structure of geospace and disturbances observed in the magnetosphere–ionosphere
(M–I) system. In this paper, a self-consistent configuration of the global convection system is considered under the real
topology as a compound system. Investigations are made based on the M–I coupling scheme by analyzing numerical results obtained
from magnetohydrodynamic (MHD) simulations which guarantee the self-consistency in the whole system under the Bv (magnetic field and velocity) paradigm. It is emphasized in the M–I coupling scheme that convection and field-aligned current
(FAC) are different aspects of same physical process characterizing the open magnetosphere. Special attention is given in
this paper to the energy supplying (dynamo) process that drives the FAC system. In the convection system, the dynamo must
be constructed from shear motion together with plasma population regimes to steadily drive the convection. Convection patterns
observed in the ionosphere are also the manifestation of achievement in global self-consistency. A primary approach to apply
these concepts to the study of geospace is to consider how the M–I system adjusts the relative motion between the compressible
magnetosphere and the incompressible ionosphere when responding to given solar-wind conditions. The above principle is also
applicable for the study of disturbance phenomena such as the substorm as well as for the study of apparently unique processes
such as the flux transfer event (FTE), the sudden commencement (SC), and the theta aurora. Finally, an attempt is made to
understand the substorm as the extension of enhanced convection under the southward interplanetary magnetic field (IMF) condition. |
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Keywords: | Convection Field-aligned current Dynamo Plasma regimes MHD simulation |
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