Precipitating Electron Energy Flux and Characteristic Energies in Jupiter's Main Auroral Region as Measured by Juno/JEDI

G. Clark, C. Tao, B. H. Mauk, J. Nichols, J. Saur, E. J. Bunce, F. Allegrini, R. Gladstone, F. Bagenal, S. Bolton, B. Bonfond, J. Connerney, R. W. Ebert, D. J. Gershman, D. Haggerty, T. Kimura, P. Kollmann, S. Kotsiaros, W. S. Kurth, S. LevinD. J. McComas, G. Murakami, C. Paranicas, A. Rymer, P. Valek

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11 Scopus citations

Abstract

The relationship between electron energy flux and the characteristic energy of electron distributions in the main auroral loss cone bridges the gap between predictions made by theory and measurements just recently available from Juno. For decades such relationships have been inferred from remote sensing observations of the Jovian aurora, primarily from the Hubble Space Telescope, and also more recently from Hisaki. However, to infer these quantities, remote sensing techniques had to assume properties of the Jovian atmospheric structure—leading to uncertainties in their profile. Juno's arrival and subsequent auroral passes have allowed us to obtain these relationships unambiguously for the first time, when the spacecraft passes through the auroral acceleration region. Using Juno/Jupiter Energetic particle Detector Instrument (JEDI), an energetic particle instrument, we present these relationships for the 30-keV to 1-MeV electron population. Observations presented here show that the electron energy flux in the loss cone is a nonlinear function of the characteristic or mean electron energy and supports both the predictions from Knight (1973, https://doi.org/10.1016/0032-0633(73)90093-7) and magnetohydrodynamic turbulence acceleration theories (e.g., Saur et al., 2003, https://doi.org/10.1029/2002GL015761). Finally, we compare the in situ analyses of Juno with remote Hisaki observations and use them to help constrain Jupiter's atmospheric profile. We find a possible solution that provides the best agreement between these data sets is an atmospheric profile that more efficiently transports the hydrocarbons to higher altitudes. If this is correct, it supports the previously published idea (e.g., Parkinson et al., 2006, https://doi.org/10.1029/2005JE002539) that precipitating electrons increase the hydrocarbon eddy diffusion coefficients in the auroral regions.

Original languageEnglish (US)
Pages (from-to)7554-7567
Number of pages14
JournalJournal of Geophysical Research: Space Physics
Volume123
Issue number9
DOIs
StatePublished - Sep 2018

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

Keywords

  • Jovian aurora
  • Juno
  • auroral acceleration
  • energetic particles
  • magnetosphere-ionosphere coupling

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    Clark, G., Tao, C., Mauk, B. H., Nichols, J., Saur, J., Bunce, E. J., Allegrini, F., Gladstone, R., Bagenal, F., Bolton, S., Bonfond, B., Connerney, J., Ebert, R. W., Gershman, D. J., Haggerty, D., Kimura, T., Kollmann, P., Kotsiaros, S., Kurth, W. S., ... Valek, P. (2018). Precipitating Electron Energy Flux and Characteristic Energies in Jupiter's Main Auroral Region as Measured by Juno/JEDI. Journal of Geophysical Research: Space Physics, 123(9), 7554-7567. https://doi.org/10.1029/2018JA025639