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Electron Densities in Jupiter's Upper Ionosphere Inferred from Juno Plasma Wave Observations
  • +15
  • William S Kurth,
  • Jeremy B. Faden,
  • Jack Hunter Waite,
  • Ali H. Sulaiman,
  • Sadie Suzanne Elliott,
  • George Blair Hospodarsky,
  • John E. P. Connerney,
  • Joshua Kammer,
  • Thomas K. Greathouse,
  • Philip Valek,
  • Frederic Allegrini,
  • Fran Bagenal,
  • Tom S. Stallard,
  • Luke Moore,
  • Drew A Coffin,
  • Omakshi Agiwal,
  • Paul Withers,
  • Scott J Bolton
William S Kurth
University of Iowa

Corresponding Author:[email protected]

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Jeremy B. Faden
University of Iowa
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Jack Hunter Waite
Waite Science LLC
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Ali H. Sulaiman
University of Minnesota
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Sadie Suzanne Elliott
University of Minnesota
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George Blair Hospodarsky
University of Iowa
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John E. P. Connerney
NASA Goddard Space Flight Center
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Joshua Kammer
SWRI
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Thomas K. Greathouse
Southwest Research Institute
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Philip Valek
Southwest Research Institute
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Frederic Allegrini
Southwest Research Institute
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Fran Bagenal
University of Colorado Boulder
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Tom S. Stallard
Northumbria University
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Luke Moore
Boston University
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Drew A Coffin
Boston University
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Omakshi Agiwal
Boston University
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Paul Withers
Boston University
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Scott J Bolton
Southwest Research Institute
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Abstract

Juno’s highly eccentric polar orbit takes it to perijove distances of ∼ 1.06 RJ on each orbit. For the first perijove, this occurred just north of the jovigraphic equator, but has precessed north by about a degree per orbit over the mission. Minimum altitudes vary from ∼3200 to 8000 km through the mission. The Waves instrument observes a number of plasma wave modes in and near the non-auroral ionosphere that provide information on the local electron number density, including electron plasma oscillations that occur at the electron plasma frequency fpe and whistler-mode hiss which has an upper frequency limit of fpe in Jupiter’s strongly magnetized inner magnetosphere. The electron plasma frequency provides the electron number density. Over the ∼59 perijoves analyzed to date, peak densities range from ∼100 to 80,000 cm-3. More recent perijoves reveal topside ionospheric peaks at latitudes greater than about 40°. The density profiles can be highly variable from one perijove to the next. And, there can be deviations from simple smooth increases and decreases with altitude within individual ionospheric passes. Spatial variations may be responsible for some of the variability, perhaps related to Jupiter’s complex, higher order magnetic field. We show the variation in ionospheric density profiles and the distribution of peak densities as a function of latitude and System III longitude as well as other geometric parameters. In addition to the complex magnetic field, possible factors affecting ionospheric density variations investigated here are ionospheric dynamos analogous to those at Earth and precipitation of energetic particles.
22 Nov 2024Submitted to ESS Open Archive
27 Nov 2024Published in ESS Open Archive