Kelvin Helmholtz Instability in Planetary Magnetospheres

Johnson, Jay R.; Wing, Simon; Delamere, P. A.

doi:10.1007/s11214-014-0085-z

Cited by 105 publications

(100 citation statements)

References 157 publications

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“…Other mechanisms in the outer magnetosphere, near the magnetopause, such as KHIs, may also have an important role in transferring momentum and energy in our observations, given that the Dungey cycle may well be less important for Jupiter than Earth [ McComas and Bagenal , , ; Delamere and Bagenal , ; Johnson et al , ].…”

Section: Resultsmentioning

confidence: 95%

The impact of an ICME on the Jovian X‐ray aurora

et al. 2016

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We report the first Jupiter X‐ray observations planned to coincide with an interplanetary coronal mass ejection (ICME). At the predicted ICME arrival time, we observed a factor of ∼8 enhancement in Jupiter's X‐ray aurora. Within 1.5 h of this enhancement, intense bursts of non‐Io decametric radio emission occurred. Spatial, spectral, and temporal characteristics also varied between ICME arrival and another X‐ray observation two days later. Gladstone et al. (2002) discovered the polar X‐ray hot spot and found it pulsed with 45 min quasiperiodicity. During the ICME arrival, the hot spot expanded and exhibited two periods: 26 min periodicity from sulfur ions and 12 min periodicity from a mixture of carbon/sulfur and oxygen ions. After the ICME, the dominant period became 42 min. By comparing Vogt et al. (2011) Jovian mapping models with spectral analysis, we found that during ICME arrival at least two distinct ion populations, from Jupiter's dayside, produced the X‐ray aurora. Auroras mapping to magnetospheric field lines between 50 and 70 RJ were dominated by emission from precipitating sulfur ions (S7+,…,14+). Emissions mapping to closed field lines between 70 and 120 RJ and to open field lines were generated by a mixture of precipitating oxygen (O7+,8+) and sulfur/carbon ions, possibly implying some solar wind precipitation. We suggest that the best explanation for the X‐ray hot spot is pulsed dayside reconnection perturbing magnetospheric downward currents, as proposed by Bunce et al. (2004). The auroral enhancement has different spectral, spatial, and temporal characteristics to the hot spot. By analyzing these characteristics and coincident radio emissions, we propose that the enhancement is driven directly by the ICME through Jovian magnetosphere compression and/or a large‐scale dayside reconnection event.

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Section: Resultsmentioning

confidence: 95%

The impact of an ICME on the Jovian X‐ray aurora

et al. 2016

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“…Borovsky and Cayton, 2011). Increasing of the specific entropy in the boundary layer suggests a nonadiabatic transport mechanism (Borovsky and Cayton, 2011;Wing et al, 2014;Johnson et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

Jupiter's deep magnetotail boundary layer

Nicolaou

McComas

Bagenal

et al. 2015

Planetary and Space Science

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“…The other primary goal of this work is to address the observed dawn‐dusk asymmetry by separating intrinsic from extrinsic sources of dawn‐dusk asymmetry in the plasma sheet population. A variety of factors related to the state of the solar wind or of the magnetosphere have been discussed as potential contributors to the observed asymmetry: solar wind speed (Wang et al, ), heavy ion distribution (Johnson et al, ), ionospheric conductance (Zhang et al, ), and solar wind IMF orientation (Adamson et al, ). We show here, using an idealized global magnetosphere, that ion entry through the geomagnetic cusp creates an intrinsic dawn‐dusk asymmetry.…”

Section: Introductionmentioning

confidence: 99%

Solar Wind Ion Entry Into the Magnetosphere During Northward IMF

et al. 2019

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Extended periods of northward interplanetary magnetic field (IMF) lead to the formation of a cold, dense plasma sheet due to the entry of solar wind plasma into the magnetosphere. Identifying the paths that the solar wind takes to enter the magnetosphere, and their relative importance has remained elusive. Any theoretical model of entry must satisfy observational constraints, such as the overall entry rate and the dawn‐dusk asymmetry observed in the cold, dense plasma sheet. We model, using a combination of global magnetohydrodynamic and test particle simulations, solar wind ion entry into the magnetosphere during northward IMF and compare entry facilitated by the Kelvin‐Helmholtz instability to cusp reconnection. For Kelvin‐Helmholtz entry we reproduce transport rates inferred from observation and kinetic modeling and find that intravortex reconnection creates buoyant flux tubes, which provides, through interchange instability, a mechanism of filling the central plasma sheet with cold magnetosheath plasma. For cusp entry we show that an intrinsic dawn‐dusk asymmetry is created during entry that is the result of alignment of the westward ion drift with the dawnward electric field typically observed during northward IMF. We show that both entry mechanisms provide comparable mass but affect entering plasma differently. The flank‐entering plasma is cold and dawn‐dusk symmetric, whereas the cusp‐entering plasma is accelerated and preferentially deflected toward dawn. The combined effect of these entry mechanisms results in a plasma sheet population that exhibits dawn‐dusk asymmetry in the manner that is seen in nature: a two‐component (hot and cold) dusk flank and hotter, broadly peaked dawn population.

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Kelvin Helmholtz Instability in Planetary Magnetospheres

Cited by 105 publications

References 157 publications

The impact of an ICME on the Jovian X‐ray aurora

The impact of an ICME on the Jovian X‐ray aurora

Jupiter's deep magnetotail boundary layer

Solar Wind Ion Entry Into the Magnetosphere During Northward IMF

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