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

• Published in: Journal of geophysical research. Space physics Vol. 123; no. 9; pp. 7554 - 7567
• Main Authors: 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., Levin, S., McComas, D. J., Murakami, G., Paranicas, C., Rymer, A., Valek, P.
• Format: Journal Article Web Resource
• Language: English
• Published: Goddard Space Flight Center American Geophysical Union 01-09-2018; Blackwell Publishing Ltd; Wiley
• Subjects: Acceleration; Atmospheric structure; auroral acceleration; Auroral zones; Aérospatiale, astronomie & astrophysique; Diffusion coefficient; Eddy diffusion; Electron energy; Energetic particles; Energy flux; Fluctuations; Fluid dynamics; Fluid flow; Flux; Hubble Space Telescope; Hydrocarbons; Jovian Aurora; Juno; Jupiter; Jupiter atmosphere; Jupiter probes; Lunar And Planetary Science And Exploration; Magnetohydrodynamic turbulence; Magnetohydrodynamics; Magnetosphere-ionosphere coupling; Physical, chemical, mathematical & earth Sciences; Physique, chimie, mathématiques & sciences de la terre; Radiation counters; Remote sensing; Remote sensing techniques; Sensing techniques; Space science, astronomy & astrophysics; Space telescopes; Spacecraft; Flux; Jupiter; Auroral
• ISSN: 2169-9380; 2169-9402; 2169-9402
• DOI: 10.1029/2018JA025639

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-kiloelectronvolts to 1-megaelectronvolts 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.