Reconfiguration timescales of ionospheric convection

Murr, D.; Hughes, W. J.

doi:10.1029/2000gl012765

Cited by 58 publications

(81 citation statements)

References 11 publications

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“…However, in the real observation, nightside convection responds immediately to the changes in IMF, as does dayside convection (Kikuchi et al 1996;Ridley et al 1997Ridley et al , 1998Murr and Hughes 2001). In this model, the center of two-cell convection moves little associated with the development of convection.…”

Section: Reconstruction Of Convection After the Southward Turning Of Imfmentioning

confidence: 99%

“…This is widely accepted because, for a long time, the ingenuity ideas on the magnetospheric convection presented by Dungey (1961) led many people to believe them unconditionally. The well-known problem for which such interpretation results in an inconsistent understanding is the reconstruction problem of ionospheric convections after the southward turning of the IMF (Ridley et al 1997;Khan and Cowley 1999;Murr and Hughes 2001;Hashimoto et al 2002).…”

Section: Reconstruction Of Convection After the Southward Turning Of Imfmentioning

confidence: 99%

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Magnetosphere–Ionosphere Convection as a Compound System

Tanaka

2007

Space Sci Rev

119

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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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Section: Reconstruction Of Convection After the Southward Turning Of Imfmentioning

confidence: 99%

Section: Reconstruction Of Convection After the Southward Turning Of Imfmentioning

confidence: 99%

Magnetosphere–Ionosphere Convection as a Compound System

Tanaka

2007

Space Sci Rev

119

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“…Radar and ground magnetometer observations demonstrated that elec-tric fields in the ionosphere show initial responses almost simultaneously in the entire ionosphere [Nishida, 1968;Ridley et al, 1998;Ruohoniemi and Greenwald, 1998;Murr and Hughes, 2001]. Observations of ground magnetic fields indicate that convection electric fields in the ionosphere propagate toward the dip equator almost instantaneously (within 25 s) [Kikuchi et al, 1996].…”

Section: Introductionmentioning

confidence: 99%

Direct measurements of the Poynting flux associated with convection electric fields in the magnetosphere

et al. 2010

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[1] Observations of Poynting fluxes associated with onset of convection electric fields are essential for understanding of electromagnetic energy transport from the solar wind toward the magnetosphere leading to changes in the convection electric field, which is one of the most fundamental parameters in the magnetosphere-ionosphere coupled system. We present Cluster multispacecraft observations of Poynting fluxes associated with abrupt changes in large-scale electric fields during sudden commencements and southward turning of the interplanetary magnetic field (IMF). The Cluster spacecraft detected Poynting fluxes dominated by the field-aligned upward component during the preliminary impulse of sudden commencements and in the initial period after southward turning of the IMF. The upward Poynting flux indicates existence of Alfvén waves transporting electromagnetic energy from the ionosphere toward the magnetosphere leading to magnetospheric convection changes. The waveguide model and global magnetohydrodynamic (MHD) simulation calculating evolution of the Poynting flux following solar wind pressure enhancements also show upward Poynting fluxes propagating from the ionosphere toward the magnetosphere faster than the propagation of compressional waves. We conclude that the ionosphere acts as a channel to transmit electromagnetic energy supplied as field-aligned currents toward a wide region in the magnetosphere-ionosphere system instantaneously, leading to changes in magnetospheric convection electric fields.

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“…[34] A typical example that shows an observational evidence for the compound nature of convection from the ionospheric observation is the controversy about the reconfiguration time scale of ionospheric convection [Lockwood and Cowley, 1999;Murr and Hughes, 2001]. It is a natural consequence from the simple Dungey's convection to believe that the convection on the nightside ionosphere cannot be driven before the tail magnetosphere knows the change of the convection.…”

Section: Observational Confirmations From Ionospheric Convectionmentioning

confidence: 99%

Formation of magnetospheric plasma population regimes coupled with the dynamo process in the convection system

Tanaka

2003

J. Geophys. Res.

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[1] Based on the magnetosphere-ionosphere (M-I) coupling scheme, convection as a compound system is considered including the generation of plasma population regimes in the magnetosphere. In these considerations, primary elements that must be set to a selfconsistent configuration are convection flows in the magnetosphere and the ionosphere, field-aligned current (FAC) systems, ionospheric currents, energy conversion processes, and plasma population regimes. The convection in the M-I coupling system is inextricably associated with the FACs. In the present results, the region-1 and region-2 FACs are driven by rP current inside the magnetosphere through plasma internal energy accumulated in the cusp and plasma sheet, respectively. In this process, mechanisms to drive the region-1 and region-2 FACs are the same two-step process; tangential Maxwell stress on the magnetopause pumps up plasma internal energy inside the magnetosphere, then plasma internal energy drives the FACs. This dynamo can be driven by a steady convection flow which is suitable to project down to the low-b regions. Thus from the magnetohydrodynamic (MHD) force balance controlling the convection, plasma population regimes appear through a requirement to form dynamo in the magnetosphere, showing that plasma population regimes are indispensable to fulfill the self-consistency in the convection system. In the model that the convection is driven directly by the linetying current, the shoulder of the magnetosphere behind the cusp, where the line-tying current is mixed with the pure Chapman-Ferraro current connected to dayside, constructs the dynamo (J.E < 0) for the region-1 FAC. In the present model with negative IMF B z , on the contrary, the Chapman-Ferraro current in this area is not directly connected with the region-1 FAC but connected with the neutral sheet current in the dayside merging region to increase plasma internal energy (J.E > 0) around the cusp. Similarly, tail theta current system acts to increase plasma internal energy in the plasma sheet through the convection. The magnetospheric model derived from this consideration enables a continuous switch over from the confinement state of geomagnetic field in the ChapmanFerraro model to the convection of Dungey model for nonzero IMF B z . In the present convection model, nearly force-free open field lines are extending from the polar cap into the lobes. Based on the convection model proposed in this paper, a suggestion is given for the substorm models in the next decade that they must develop from a modular model to a globally self-consistent model. Citation: Tanaka, T., Formation of magnetospheric plasma population regimes coupled with the dynamo process in the convection system,

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Reconfiguration timescales of ionospheric convection

Cited by 58 publications

References 11 publications

Magnetosphere–Ionosphere Convection as a Compound System

Magnetosphere–Ionosphere Convection as a Compound System

Direct measurements of the Poynting flux associated with convection electric fields in the magnetosphere

Formation of magnetospheric plasma population regimes coupled with the dynamo process in the convection system

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