The Jovian ionospheric conductivity derived from a broadband precipitated electron distribution
- 1LPAP, STAR Institute, Université de Liège, Liège, Belgium (guillaume.sicorello@uliege.be)
- 2Faculty of Physics, University Observatory, Munich, Germany (l.gkouvelis@uliege.be)
- 3Southwest Research Institute San Antonio, Texas, USA (randy.gladstone@swri.org)
- 4Physics and Astronomy Department, University of Texas at San Antonio, Texas, USA
- 5Institute of Geophysics and Meteorology, University of Cologne, Cologne, Germany (asalvet1@uni-koeln.de)
The Pedersen ionospheric conductivity at Jupiter can be computed using a precipitated electron flux either obtained by direct in situ measurements or inferred from UV auroral spectra (Gérard et al., 2020). In the latter case, a mono-energetic distribution was used to represent the electron flux. However, based on the Juno spacecraft recent findings, it appears that the impinging electron flux is best approximated with a broadband distribution (Mauk et al., 2017; Salveter et al., 2022). In this study, we estimate the impact of such a distribution on the conductivity. In particular, we examine the ratio between the Pedersen conductances computed with a mono-energetic and with a broadband distribution, which can be modelled with a kappa distribution. A similar methodology as in Gérard et al. (2020) is followed to compute the conductances. The altitude distributions of H, H2 and CH4, included in the atmosphere model, are taken from Grodent et al’s (2001) model.
Among other results, we find that the ratio between conductances depends on the electron mean energy of the precipitating electrons population. For a mono-energetic distribution, an optimal energy exists, around 30-40 keV, for which the conductance arising from the precipitation is maximum. If the mean electron energy is well below this optimal energy, the conductance calculated for a kappa distribution is enhanced compared to the mono-energetic case because part of the electron energy distribution reaches this optimal level. The conductance is also underestimated for a mono-energetic electron precipitation well above the optimal value. The opposite trend is observed around the optimal energy as most of the electrons of the broadband distribution have either lower or higher energies, while all electrons of the mono-energetic distribution have an energy close to the optimum.
In conclusion, compared to a realistic broadband electron distribution on Jupiter, a mono-energetic distribution tends to overestimate the conductivity for mean energies in the 7 – 450 keV range and to underestimate it outside this range. In the future, this new relationship between the mean energy and the conductivity will be used to update the conductance maps built from the data from Juno.
References:
Gérard, J.‐C., Gkouvelis, L., Bonfond, B. et al. (2020). J. Geophys. Res Space Phys., 125, e2020JA028142. https://doi.org/10.1029/2020JA028142.
Grodent, D., Waite, J. H. and Gérard, J.-C. (2001). J. Geophys. Res., 106 (A7), 12933–12952. https://doi.org/10.1029/2000JA900129.
Mauk, B., Haggerty, D., Paranicas, C. et al. (2017). Nature, 549, 66–69. https://doi.org/10.1038/nature23648.
Salveter, A., Saur, J., Clark, G. et al. (2022). J. Geophys. Res Space Phys., 127, e2021JA030224. https://doi.org/10.1029/2021JA030224.
How to cite: Sicorello, G., Bonfond, B., Gérard, J.-C., Grodent, D., Gkouvelis, L., Gladstone, R., and Salveter, A.: The Jovian ionospheric conductivity derived from a broadband precipitated electron distribution, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12662, https://doi.org/10.5194/egusphere-egu23-12662, 2023.
