Magnetic flux circulation in the rotationally driven giant magnetospheres

Delamere, P. A.; Otto, A.; Ma, Xuanye; Bagenal, F.; Wilson, R.

doi:10.1002/2015ja021036

Cited by 82 publications

(137 citation statements)

References 73 publications

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“…This process may explain the arcs and generally disturbed auroral morphology poleward of the main oval in the few days following the onset of a compression [ Nichols et al , ]. We note that a similar conjecture has also been recently put forward by Delamere et al []. Examination of the effects of compressions and expansions will be conducted in future works.…”

Section: Discussionsupporting

confidence: 73%

A model of force balance in Jupiter's magnetodisc including hot plasma pressure anisotropy

2015

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We present an iterative vector potential model of force balance in Jupiter's magnetodisc that includes the effects of hot plasma pressure anisotropy. The fiducial model produces results that are consistent with Galileo magnetic field and plasma data over the whole radial range of the model. The hot plasma pressure gradient and centrifugal forces dominate in the regions inward of ∼20 RJ and outward of ∼50 RJ, respectively, while for realistic values of the pressure anisotropy, the anisotropy current is either the dominant component or at least comparable with the hot plasma pressure gradient current in the region in between. With the inclusion of hot plasma pressure anisotropy, the ∼1.2 and ∼2.7° shifts in the latitudes of the main oval and Ganymede footprint, respectively, associated with variations over the observed range of the hot plasma parameter Kh, which is the product of hot pressure and unit flux tube volume, are comparable to the shifts observed in auroral images. However, the middle magnetosphere is susceptible to the firehose instability, with peak equatorial values of βh∥e−βh⊥e≃1 − 2, for Kh=2.0 − 2.5 × 107 Pa m T−1. For larger values of Kh,βh∥e−βh⊥e exceeds 2 near ∼25 RJ and the model does not converge. This suggests that small‐scale plasmoid release or “drizzle” of iogenic plasma may often occur in the middle magnetosphere, thus forming a significant mode of plasma mass loss, alongside plasmoids, at Jupiter.

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Section: Discussionsupporting

confidence: 73%

A model of force balance in Jupiter's magnetodisc including hot plasma pressure anisotropy

2015

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“…The magnetic flux circulation is also a possible auroral brightening mechanism [Delamere and Bagenal, 2013;Delamere et al, 2015]. Delamere and Bagenal [2013] proposed that the solar wind compression enhances transport of dayside closed magnetic flux to the nightside and subsequent tail reconnection.…”

Section: Discussionmentioning

confidence: 99%

Characteristics of solar wind control on Jovian UV auroral activity deciphered by long‐term Hisaki EXCEED observations: Evidence of preconditioning of the magnetosphere?

Kita

Kimura

Tao

et al. 2016

Geophysical Research Letters

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While the Jovian magnetosphere is known to have the internal source for its activity, it is reported to be under the influence of the solar wind as well. Here we report the statistical relationship between the total power of the Jovian ultraviolet aurora and the solar wind properties found from long‐term monitoring by the spectrometer EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) on board the Hisaki satellite. Superposed epoch analysis indicates that auroral total power increases when an enhanced solar wind dynamic pressure hits the magnetosphere. Furthermore, the auroral total power shows a positive correlation with the duration of a quiescent interval of the solar wind that is present before a rise in the dynamic pressure, more than with the amplitude of dynamic pressure increase. These statistical characteristics define the next step to unveil the physical mechanism of the solar wind control on the Jovian magnetospheric dynamics.

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“…Delamere et al . [] have even argued that smaller‐scale Vasyliunas‐type reconnection occurs commonly throughout the dayside and dusk sectors. The in situ evidence for the operation of the Dungey cycle has been considerably sparser.…”

Section: Introductionmentioning

confidence: 99%

Sustained lobe reconnection in Saturn's magnetotail

et al. 2015

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The degree to which solar wind driving may affect Saturn's magnetosphere is not yet fully understood. We present observations that suggest that under some conditions the solar wind does govern the character of the plasma sheet in Saturn's outer magnetosphere. On 16 September 2006, the Cassini spacecraft, at a radial distance of 37 Rs near local midnight, observed a sunward flowing ion population for ~5 h, which was accompanied by enhanced Saturn Kilometric Radiation emissions. We interpret this beam as the outflow from a long‐lasting episode of Dungey‐type reconnection, i.e., reconnection of previously open flux containing magnetosheath material. The beam occurred in the middle of a several‐day interval of SKR activity and enhanced lobe magnetic field strength, apparently caused by the arrival of a solar wind compression region with significantly higher than average dynamic pressure. The arrival of the high‐pressure solar wind also marked a change in the composition of the plasma‐sheet plasma, from water‐group‐dominated material clearly of inner‐magnetosphere origin to material dominated by light‐ion composition, consistent with captured magnetosheath plasma. This event suggests that under the influence of prolonged high solar wind dynamic pressure, the tail plasma sheet, which normally consists of inner‐magnetospheric plasma, is eroded away by ongoing reconnection that then involves open lobe field lines. This process removes open magnetic flux from the lobes and creates a more Earth‐like, Dungey‐style outer plasma sheet dominantly of solar wind origin. This behavior is potentially a recurrent phenomenon driven by repeating high‐pressure streams (corotating interaction regions) in the solar wind, which also drive geomagnetic storms at Earth.

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Magnetic flux circulation in the rotationally driven giant magnetospheres

Cited by 82 publications

References 73 publications

A model of force balance in Jupiter's magnetodisc including hot plasma pressure anisotropy

A model of force balance in Jupiter's magnetodisc including hot plasma pressure anisotropy

Characteristics of solar wind control on Jovian UV auroral activity deciphered by long‐term Hisaki EXCEED observations: Evidence of preconditioning of the magnetosphere?

Sustained lobe reconnection in Saturn's magnetotail

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