A comparison of a model for the theta aurora with observations from Polar, Wind, and SuperDARN

Chang, S.-W.; Scudder, J. D.; Sigwarth, J. B.; Frank, L. A.; Maynard, N. C.; Burke, William J.; Peterson, W. K.; Shelley, E. G.; Friedel, R. H. W.; Blake, J. B.; Greenwald, R. A.; Lepping, R. P.; Sofko, G. J.; Villain, J. P.; Lester, M.

doi:10.1029/97ja02255

Cited by 57 publications

(132 citation statements)

References 51 publications

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“…Slinker et al (2001) first applies the global MHD simulation to the formation of theta aurora and showed that the TPA is formed below closed field lines that break off from the main oval and convect across the polar cap. Their simulation seems to support the results of Chang et al (1998). Also their results confirmed the previous expectation that closed field lines on the TPA are connected in the magnetosphere to the closed field finger that separates two open lobes.…”

Section: Reconstruction Of Convection For Different Imf B Y and The Tsupporting

confidence: 81%

“…In general, the TPA is predominantly a northward IMF phenomenon associated with large positive IMF B z , and greater IMF magnitude than normal (Cumnock et al 1997;Chang et al 1998). The precipitating electrons for the TPA are less energetic than those for the nightside auroral arcs, and called as the polar shower (Winningham and Heikkila 1974).…”

Section: Reconstruction Of Convection For Different Imf B Y and The Tmentioning

confidence: 99%

“…5). The merging location moves closer to the equator associated with B z negative excursion (Newell and Meng 1995), or jumps to other side of magnetic noon associated with a B y sign change (Chang et al 1998) (Chang et al 1998). Thus, the TPA can be formed along the closed field line region that separates old and new open sections.…”

Section: Reconstruction Of Convection For Different Imf B Y and The Tmentioning

confidence: 99%

“…In this model, a contracted polar cap is more suitable before the theta aurora initiation, because the newly opened region must be well separated from the previously open region. Chang et al (1998) pointed out another condition for theta aurora initiation that |B y | > |B z | must continue for ∼10 min after the IMF change.…”

Section: Reconstruction Of Convection For Different Imf B Y and The Tmentioning

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 For Different Imf B Y and The Tsupporting

confidence: 81%

Section: Reconstruction Of Convection For Different Imf B Y and The Tmentioning

confidence: 99%

Section: Reconstruction Of Convection For Different Imf B Y and The Tmentioning

confidence: 99%

Section: Reconstruction Of Convection For Different Imf B Y and The Tmentioning

confidence: 99%

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Magnetosphere–Ionosphere Convection as a Compound System

Tanaka

2007

Space Sci Rev

119

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“…Several models have been created attempting to explain transpolar arcs (e.g. Chang et al, 1998;Newell et al, 1999;Kullen, 2000;Slinker et al, 2001;Kullen and Janhunen, 2004;Naehr and Toffoletto, 2004). However, since not all polar arcs are transpolar, care must be taken not to confuse the different types when discussing their occurrence, the corresponding magnetospheric topology, or the physical mechanisms causing them.…”

Section: Introductionmentioning

confidence: 99%

Transpolar aurora: time evolution, associated convection patterns, and a possible cause

et al. 2005

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Abstract. We present two event studies illustrating the detailed relationships between plasma convection, field-aligned currents, and polar auroral emissions, as well as illustrating the influence of the Interplanetary Magnetic Field's ycomponent on theta aurora development. The transpolar arc of the theta aurorae moves across the entire polar region and becomes part of the opposite side of the auroral oval. Electric and magnetic field and precipitating particle data are provided by DMSP, while the POLAR UVI instrument provides measurements of auroral emissions. Ionospheric electrostatic potential patterns are calculated at different times during the evolution of the theta aurora using the KTH model. These model patterns are compared to the convection predicted by mapping the magnetopause electric field to the ionosphere using the Paraboloid Model of the magnetosphere. The model predicts that parallel electric fields are set up along the magnetic field lines projecting to the transpolar aurora. Their possible role in the acceleration of the auroral electrons is discussed.

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Global MHD modeling of ionospheric convection and field‐aligned currents associated with IMF B_y triggered theta auroras

et al. 2014

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Using numerical magnetohydrodynamic simulations, we investigate the evolution of ionospheric convection and field-aligned currents (FACs) when θ auroras are formed in response to interplanetary magnetic field (IMF) B y transitions. When the polarity of IMF B y switches abruptly during northward IMF periods, the crossbar of the θ aurora is isolated from the flankside auroral oval and drifts into the polar cap. This drift motion is involved in a large round cell associated with new IMF B y , with sunward convection residing only on the dayside tip of the crossbar. There exists an IMF B y -controlled large-scale FAC system on the crossbar. When the θ aurora is drifting duskward (dawnward), the FACs are located on the dawnside (duskside) boundary of the crossbar adjacent to the "new" lobe. In contrast, the magnetospheric source region of the crossbar FAC system is located on the duskside (dawnside) boundary of the protruded plasma sheet adjacent to the "old" lobe. In the source region, plasma thermal pressure feeds the electromagnetic energy of FACs, and these processes can be interpreted as coupling of slow mode and Alfvén mode disturbances. In the ionosphere, the crossbar-associated FACs close with part of the region 1 currents associated with the new crescent cell. The magnetospheric source of that part of the region 1 FACs is located on the plasma sheet boundary and the magnetopause both adjacent to the new lobe. Dynamo processes in the old-lobe side and the new-lobe side work together to drive the ionospheric drift motion of the crossbar.

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A comparison of a model for the theta aurora with observations from Polar, Wind, and SuperDARN

Cited by 57 publications

References 51 publications

Magnetosphere–Ionosphere Convection as a Compound System

Magnetosphere–Ionosphere Convection as a Compound System

Transpolar aurora: time evolution, associated convection patterns, and a possible cause

Global MHD modeling of ionospheric convection and field‐aligned currents associated with IMF B_y triggered theta auroras

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A comparison of a model for the theta aurora with observations from Polar, Wind, and SuperDARN

Cited by 57 publications

References 51 publications

Magnetosphere–Ionosphere Convection as a Compound System

Magnetosphere–Ionosphere Convection as a Compound System

Transpolar aurora: time evolution, associated convection patterns, and a possible cause

Global MHD modeling of ionospheric convection and field‐aligned currents associated with IMF By triggered theta auroras

Contact Info

Product

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Global MHD modeling of ionospheric convection and field‐aligned currents associated with IMF B_y triggered theta auroras