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Simultaneous UV Images and High-latitude Particle and Field Measurements During an Auroral Dawn Storm at Jupiter
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  • Robert Wilkes Ebert,
  • Thomas K. Greathouse,
  • George Clark,
  • Frederic Allegrini,
  • Fran Bagenal,
  • Scott J Bolton,
  • Bertrand Bonfond,
  • John E. P. Connerney,
  • Randy Gladstone,
  • Vincent Hue,
  • Masafumi Imai,
  • William S Kurth,
  • Steven M. Levin,
  • Philippe Louarn,
  • Barry H. Mauk,
  • David J. McComas,
  • Christopher P. Paranicas,
  • Ali H. Sulaiman,
  • Jamey R. Szalay,
  • Michelle F. Thomsen,
  • Robert J. Wilson
Robert Wilkes Ebert
Southwest Research Institute, Southwest Research Institute

Corresponding Author:[email protected]

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Thomas K. Greathouse
Southwest Research Institute, Southwest Research Institute
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George Clark
Johns Hopkins University Applied Physics Laboratory, Johns Hopkins University Applied Physics Laboratory
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Frederic Allegrini
Southwest Research Institute, Southwest Research Institute
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Fran Bagenal
University of Colorado Boulder, University of Colorado Boulder
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Scott J Bolton
Southwest Research Institute, Southwest Research Institute
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Bertrand Bonfond
Université de Liège, Université de Liège
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John E. P. Connerney
NASA Goddard Space Flight Center, NASA Goddard Space Flight Center
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Randy Gladstone
Southwest Research Institute, Southwest Research Institute
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Vincent Hue
SWRI, SWRI
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Masafumi Imai
University of Iowa, University of Iowa
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William S Kurth
University of Iowa, University of Iowa
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Steven M. Levin
Jet Propulsion Laboratory, Jet Propulsion Laboratory
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Philippe Louarn
IRAP, IRAP
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Barry H. Mauk
Johns Hopkins University, Johns Hopkins University
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David J. McComas
Princeton University, Princeton University
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Christopher P. Paranicas
Johns Hopkins University, Johns Hopkins University
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Ali H. Sulaiman
University of Iowa, University of Iowa
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Jamey R. Szalay
Princeton University, Princeton University
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Michelle F. Thomsen
Planetary Science Institute, Planetary Science Institute
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Robert J. Wilson
University of Colorado Boulder, University of Colorado Boulder
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Abstract

We present multi-instrument Juno observations on day-of-year 86, 2017 that link particles and fields in Jupiter’s polar magnetosphere to transient UV emissions in Jupiter’s northern auroral region known as dawn storms. Juno ranged from 42ºN - 51ºN in magnetic latitude and 5.8 – 7.8 jovian radii (1 RJ = 71,492 km) during this period. These dawn storm emissions consisted of two separate, elongated structures which extended into the nightside, rotated with the planet, had enhanced brightness (up to at least 1.4 megaRayleigh) and high color ratios. The color ratio is a proxy for the atmospheric penetration depth and therefore the energy of the electrons that produce the UV emissions. Juno observed electrons and ions on magnetic field lines mapping to these emissions. The electrons were primarily field-aligned, bi-directional, and, at times, exhibited sudden intensity decreases below ~10 keV coincident with intensity enhancements up to energies of ~1000 keV, consistent with the high color ratio observations. The more energetic electron distributions had characteristic energies of ~160 – 280 keV and downward energy fluxes (~70 – 135 mW/m2) that were a significant fraction needed to produce the UV emissions for this event. Magnetic field perturbations up to ~0.7% of the local magnetic field showing evidence of upward and downward field-aligned currents, whistler mode waves, and broadband kilometric radio emissions were also observed along Juno’s trajectory during this timeframe. These high latitude observations show similarities to those in the equatorial magnetosphere associated with dynamics processes such as interchange events, plasma injections, and/or tail reconnection.
Dec 2021Published in Journal of Geophysical Research: Space Physics volume 126 issue 12. 10.1029/2021JA029679