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. Levin; D. J. McComas; G. Murakami; C. Paranicas; A. Rymer; P. Valek

doi:10.1029/2018JA025639

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

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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, …

Journal of geophysical research. Space physics, Vol.123(9), pp.7554-7567

09/2018

DOI: 10.1029/2018JA025639

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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. Key Points Measured profiles of the energetic electron energy flux and characteristic energies in Jupiter's main auroral region Data help constrain Jovian auroral acceleration theories ‐ various aspects in agreement with both Knight and MHD turbulence predictions Comparisons to Hisaki remote sensing data reveal that the hydrocarbon eddy diffusion coefficient in the auroral region may be enhanced

auroral acceleration

energetic particles

Jovian aurora

Juno

magnetosphere‐ionosphere coupling

Details

Title: Subtitle: Precipitating Electron Energy Flux and Characteristic Energies in Jupiter's Main Auroral Region as Measured by Juno/JEDI
Creators: G. Clark - The Johns Hopkins University Applied Physics Laboratory
C. Tao - National Institute of Information and Communications Technology
B. H. Mauk - Johns Hopkins University Applied Physics Laboratory
J. Nichols - University of Leicester
J. Saur - University of Cologne
E. J. Bunce - University of Leicester
F. Allegrini - Southwest Research Institute
R. Gladstone - Southwest Research Institute
F. Bagenal - Laboratory for Atmospheric and Space Physics
S. Bolton - Southwest Research Institute
B. Bonfond - University of Liège
J. Connerney - Space Research Corporation
R. W. Ebert - Southwest Research Institute
D. J. Gershman - Goddard Space Flight Center
D. Haggerty - Johns Hopkins University Applied Physics Laboratory
T. Kimura - Tokyo University of Science
P. Kollmann - Johns Hopkins University Applied Physics Laboratory
S. Kotsiaros - Goddard Space Flight Center
W. S. Kurth - University of Iowa
S. Levin - Jet Propulsion Laboratory
D. J. McComas - Southwest Research Institute
G. Murakami - Japan Aerospace Exploration Agency
C. Paranicas - Johns Hopkins University Applied Physics Laboratory
A. Rymer - Johns Hopkins University Applied Physics Laboratory
P. Valek - Southwest Research Institute
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.123(9), pp.7554-7567
DOI: 10.1029/2018JA025639
ISSN: 2169-9380
eISSN: 2169-9402
Number of pages: 14
Grant note: Royal Society Wolfson Research Merit Award STFC Consolidated (ST/N000749/1)
Language: English
Date published: 09/2018
Academic Unit: Physics and Astronomy
Record Identifier: 9984455366002771

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