Applications of the Jupiter Global Ionosphere‐Thermosphere Model: A case study of auroral electron energy deposition

Abstract

We investigate auroral energy deposition by using a nonhydrostatic global atmospheric model coupled to a two‐stream electron transport model. We present several electron beam study cases, discussing energy flux and electron energy effects on the ion and neutral densities, the atmospheric thermal profile, H3+ and hydrocarbon infrared (IR) emissions, H2 far ultraviolet (FUV) emissions and color ratios, and vibrationally excited molecular hydrogen. Using the nonhydrostatic Jupiter Global Ionosphere‐Thermosphere Model, we find that FUV spectral characteristics consistent with previous Hubble Space Telescope results derive primarily from electrons with energies above 10 keV, over energy fluxes of 10–100 erg/cm2 s, while IR emissions are predominantly due to electrons with energies below 10 keV, over energy fluxes of 10–100 erg/cm2 s. Electrons with energies below about 10 keV produce enough H2(ν) to deplete the H+ population, modifying the ionospheric composition, and consequently the H3+ emissions, which can be used to directly relate H2 vibrational excitation to auroral observations. New observations by Juno will provide better electron energy distributions to constrain the electron energy spectrum and magnitude at the upper boundary of the model and simultaneously provide a determination of the FUV and IR spectra that can be cross‐correlated with the observations.

Jupiter's Enigmatic Ionosphere: Electron Density Profiles From the Pioneer, Voyager, and Galileo Radio Occultation Experiments

“…They continued to evolve following the Voyager encounters, and most recently after the Galileo series of occultation experiments. A comprehensive, recent modeling treatment appears in Egert et al (2017). To help focus discussion, we show in Figure 15 a representative set of profiles for the constituents of the neutral atmosphere, together with ion and electron density profiles produced by photo-ionization and associated atmospheric chemistry (taken from Figure 7 in Moore et al [2019]).…”

Juno In Situ Observations Above the Jovian Equatorial Ionosphere

“…Some of the profiles show sharp variations (up to two orders of magnitude) within altitude changes of <100 km. None of the profiles are in the auroral region where the ionospheric densities are expected to increase (Bougher et al, 2005; Egert et al, 2017). Models of the upper atmosphere and ionosphere tend to focus on either heating or radiative processes rather than trying to match ionospheric profiles (again, reviewed by Yelle & Miller, 2004).…”