How is the Jovian main auroral emission affected by the solar wind?

Chané, Emmanuel; Saur, Joachim; Keppens, Rony; Poedts, Stefaan

doi:10.1002/2016ja023318

Cited by 42 publications

(75 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As plasma rotates through dawn into the dayside magnetosphere, it is constrained by the magnetopause and forced closer to the planet. As a consequence its velocity increases, and the

\overset{j}{true} \times \overset{B}{true}

force required to keep the plasma in corotation is decreased (Chané et al, ; Kivelson & Southwood, ; Walker & Ogino, ). Additionally, the solar wind dynamic pressure acts to balance the outward radial stresses, and so weaker azimuthal currents are present in the dayside magnetosphere.…”

Section: Discussionmentioning

confidence: 99%

Local Time Asymmetries in Jupiter's Magnetodisc Currents

et al. 2020

View full text Add to dashboard Cite

We present an investigation into the currents within the Jovian magnetodisc using all available spacecraft magnetometer data up until 28 July 2018. Using automated data analysis processes as well as the most recent intrinsic field and current disk geometry models, a full local time coverage of the magnetodisc currents using 7,382 lobe traversals over 39 years is constructed. Our study demonstrates clear local time asymmetries in both the radial and azimuthal height‐integrated current densities throughout the current disk. Asymmetries persist within 30 R normalJ where most models assume axisymmetry. Inward radial currents are found in the previously unmapped dusk and noon sectors. Azimuthal currents are found to be weaker in the dayside magnetosphere than the nightside, in agreement with global magnetohydrodynamic simulations. The divergence of the azimuthal and radial currents indicates that downward field‐aligned currents exist within the outer dayside magnetosphere. The presence of azimuthal currents is shown to highly influence the location of the field‐aligned currents, which emphasizes the importance of the azimuthal currents in future magnetosphere‐ionosphere coupling models. Integrating the divergence of the height‐integrated current densities, we find that 1.87 MA R normalJ−2 of return current density required for system closure is absent.

show abstract

“…As plasma rotates through dawn into the dayside magnetosphere, it is constrained by the magnetopause and forced closer to the planet. As a consequence its velocity increases, and the

\overset{j}{true} \times \overset{B}{true}

Section: Discussionmentioning

confidence: 99%

Local Time Asymmetries in Jupiter's Magnetodisc Currents

et al. 2020

View full text Add to dashboard Cite

show abstract

“…In order to circumvent the difficulty of numerically integrating the MHD equations in the presence of strong spatial gradients (without drastically reducing the spatial resolution of the numerical grid), Tanaka () proposed to solve the MHD equations by splitting the global magnetic field B into an intrinsic potential magnetic field B 0 and a residual magnetic field B 1 . This technique has been widely applied to MHD simulations of planetary magnetospheres since then (e.g., for recent studies of Saturn, Jia et al, ; Jupiter, Chané et al, ; or Uranus, Cao & Paty, ). However, in Tanaka (), the background magnetic field B 0 was assumed to be potential (i.e., current‐free) and time independent.…”

Section: Simulation Modelmentioning

confidence: 99%

Three‐Dimensional Magnetohydrodynamic Simulations of the Solar Wind Interaction With a Hyperfast‐Rotating Uranus

2018

View full text Add to dashboard Cite

We present magnetohydrodynamic simulations of a fast‐rotating planetary magnetosphere reminiscent of the planet Uranus at solstice, that is, with the spin axis pointing to the Sun. We impose a 10 times faster rotation than for Uranus, in order to emphasize the effects of rotation on the magnetospheric tail without the need of an excessively large simulation domain while keeping the qualitative aspects of a supersonic magnetized solar wind interacting with a fast‐rotating magnetosphere. We find that a complex helical Alfvénic structure propagates downstream at a velocity exceeding the plasma velocity in the magnetosheath. Similarly, the reconnection regions, which mediate the interaction of the planetary magnetic field and the interplanetary magnetic field, do also form a helical structure with the same downstream velocity but a 2 times larger pitch. We speculate that the magnetic field of the helical structure connected to the interplanetary magnetic field asymptotically reduces the phase velocity of the helical structure toward the tailward velocity in the magnetosheath. For our simulations we use the MPI‐AMRVAC code which we enhanced with a time‐dependent background magnetic field in the splitting of the magnetic field.

show abstract

“…Observations from these intervals suggest an increase in the UV auroral brightness and hectometric auroral radio emission intensity following the arrival of an interplanetary shock (Clarke et al, ; Gurnett et al, ; Nichols et al, , ), in conflict with the predictions of Cowley and Bunce () and Southwood and Kivelson (). Recent MHD simulations also suggest that the main auroral emission would brighten in response to an increase in solar wind dynamic pressure (Chané et al, ). However, both the UV auroral brightness and auroral radio emissions can change in response to changes internal to the magnetosphere without any external solar wind activity.…”

Section: Background and Motivationmentioning

confidence: 99%

Long‐Term Variability of Jupiter's Magnetodisk and Implications for the Aurora

et al. 2017

View full text Add to dashboard Cite

Observations of Jupiter's UV auroral emissions collected over several years show that the ionospheric positions of the main emission and the Ganymede footprint can vary by as much as 3° in latitude. One explanation for this shift is a change of Jupiter's current sheet current density, which would alter the amount of field line stretching and displace the ionospheric mapping of field lines from a given radial distance in the magnetosphere. In this study we measure the long‐term variability of Jupiter's magnetodisk using Galileo magnetometer data collected from 1996 to 2003. Using the Connerney et al. (1981) current sheet model, we calculate the current sheet density parameter that gives the best fit to the data from each orbit and find that the current density parameter varies by about 15% of its average value during the Galileo era. We investigate possible relationships between the observed current sheet variability and quantities such as Io's plasma torus production rate inferred from volcanic activity and external solar wind conditions extrapolated from data at 1 AU but find only a weak correlation. Finally, we trace Khurana (1997) model field lines to show that the observed changes in Jupiter's current sheet are sufficient to shift the ionospheric footprint of Ganymede and main auroral emission by a few degrees of latitude, consistent with the magnitude of auroral variability observed by Hubble Space Telescope (HST). However, we find that the measured auroral shifts in HST images are not consistent with concurrent changes in the current density parameter measured by Galileo.

show abstract

How is the Jovian main auroral emission affected by the solar wind?

Cited by 42 publications

References 74 publications

Local Time Asymmetries in Jupiter's Magnetodisc Currents

Local Time Asymmetries in Jupiter's Magnetodisc Currents

Three‐Dimensional Magnetohydrodynamic Simulations of the Solar Wind Interaction With a Hyperfast‐Rotating Uranus

Long‐Term Variability of Jupiter's Magnetodisk and Implications for the Aurora

Contact Info

Product

Resources

About