A fine-structure hydrogen physical chemistry model for study of the atmosphere and ionosphere of Jupiter

The outer planet thermospheres have temperatures elevated above those theoretically expected from simple, solar EUV radiation models. Analysis of observations of Jupiter by Voyager and Galileo has obtained thermospheric temperatures at least six times higher than predicted. Similar high temperature thermospheres have been determined for all the giant outer planets. The heating mechanism required to produce these elevated temperatures is unknown. This dissertation research applies a fine-structure hydrogen physical chemistry model to the Jupiter and Uranus thermospheres to predict observed constituent partitioning and explain the energy budget required to produce the elevated outer planet thermospheric temperatures.; Past theories for the heating mechanism have been constrained by the day-night asymmetry observed in the outer planet EUV emissions. Modeling the solar energy deposition process has been problematic; a symptom of the difficulty appears in previous attempts to model the Jovian ionosphere, which have resulted in electron densities an order of magnitude greater than observation. Evidence from the Cassini UVIS Jupiter dayglow observations indicates that electrons, not solar-photons, are the dominant source of the H and H2 EUV emissions. Electrons deposit energy into the system primarily through dissociation of H2 into kinetically hot products. Solar photo-electrons, produced efficiently by the ionization of H2 in a non-LTE distribution, are required to produce the observed ionospheric electrons. An assumed source of hot electrons is required to reproduce the observed EUV H2 band emissions and the elevated outer planet temperatures. Because the outer planet thermospheres are not in LTE, fine-structure chemistry is vital to develop accurate models of the gas volume.; A code has been developed at the University of Southern California to make volumetric calculations of steady-state partitioning in an excited gas. The developed code utilizes a hydrogen physical chemistry structure operating at the rotational level to define the state structure of the gas, tracking detail in energy budget and predicting all emission processes in the system. The hydrogen chemistry and the model code have been applied to the Jupiter and Uranus upper atmospheres to predict emission intensities for comparison to observations of the Jupiter and Uranus dayglows.