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Local Time Dependence of Jupiter's Polar Auroral Emissions Observed by Juno UVS
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  • Thomas K. Greathouse,
  • Randy Gladstone,
  • Maarten H. Versteeg,
  • Vincent Hue,
  • Joshua Kammer,
  • Rohini S Giles,
  • Michael W. Davis,
  • Scott J Bolton,
  • Steven M. Levin,
  • John E. P. Connerney,
  • Jean-Claude M.C. Gérard,
  • Denis Grodent,
  • Bertrand Bonfond,
  • Emma Bunce,
  • Marissa F. Vogt
Thomas K. Greathouse
Southwest Research Institute

Corresponding Author:[email protected]

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Randy Gladstone
Southwest Research Institute
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Maarten H. Versteeg
Southwest Research Institute
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Vincent Hue
Southwest Research Institute
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Joshua Kammer
SWRI
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Rohini S Giles
Southwest Research Institute
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Michael W. Davis
Southwest Research Institute
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Scott J Bolton
Southwest Research Institute
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Steven M. Levin
Jet Propulsion Laboratory
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John E. P. Connerney
NASA Goddard Space Flight Center
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Jean-Claude M.C. Gérard
Université de Liège
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Denis Grodent
Université de Liège
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Bertrand Bonfond
Université de Liège
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Emma Bunce
University of Leicester
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Marissa F. Vogt
Boston University
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Abstract

Auroral brightness and color ratio imagery, captured using the Juno mission’s Ultraviolet Spectrograph, display intense emissions poleward of Jupiter’s northern main emission, and these are split into two distinctly different spectral or “color ratio” regimes. The most poleward region, designated the “swirl region” by Grodent et al. (2003), exhibits a high color ratio, while low color ratio emissions are found within the collar around the swirl region but still poleward of the main emission. We confirm the apparent strong magnetospheric local time control within the polar collar (Grodent et al., 2003), with the dusk side bright “active region” emissions extending from ~11 to 22 hr of magnetospheric local time. These bright emissions dim by at least an order of magnitude between ~0 and 11 hr magnetospheric local time, in the midnight to dawn side “dark region”. This magnetospheric local time structure holds true even when the entire northern oval is located on the night side of the planet (in ionospheric local time), a geometry unstudied prior to Juno, as it is unobservable from Earth. The swirl region brightens at ionospheric dawn (~5-7 ionospheric local time) and diminishes or completely disappears at ionospheric local times of ~20 to 22 hrs. Finally, the southern auroral polar emissions appear to share all of the local time dependencies of its northern counterpart, but at a reduced intensity.
Dec 2021Published in Journal of Geophysical Research: Planets volume 126 issue 12. 10.1029/2021JE006954