Gravity waves in the upper atmosphere of Jupiter

Two aspects of the aeronomy of Jupiter's upper atmosphere are investigated in this dissertation: (i) the contribution of internal atmospheric gravity waves to the energy budget of the thermosphere of Jupiter and (ii) the interaction of gravity waves with ionospheric plasma with direct implications for Jupiter's ionosphere.; Heating Jupiter's thermosphere by viscous dissipation of upward propagating gravity waves is evaluated with correct formulations of total energy conservation and the total wave induced vertical energy flux. In contrast to the results of Young et al. (1997), our calculations, with their wave amplitudes and parameters, yield a maximum thermospheric temperature of T = 380 K at 552 km above the 1 bar level in comparison to the Galileo probe inferred temperature of T = 900 K. Therefore, it is concluded that gravity waves may not be solely responsible for the observed steep temperature gradient just above the homopause. The large sensible heat flux associated with dissipating gravity waves generates net heating of the lower regions and net cooling of the upper regions of wave dissipation due to energy redistribution. The transition from net heating to net cooling occurs at the level of constant wave amplitude. In regions of substantial wave dissipation the local cooling rate due to sensible heat flux divergence can exceed the local heating due to convergence of the Eliassen-Palm flux to produce (1) net cooling of and (2) a distinct temperature decrease (≈65 K) in the topside thermosphere. To simulate Jupiter's thermospheric temperature profile inferred from the Galileo probe data with (1) gravity wave heating only, (2) 100% conversion of wave energy to internal energy, and (3) radiative cooling by $H+3$ near-IR emission ∼0.1 erg cm−2s−1 , gravity waves must deposit their energy high in the thermosphere with peak heating occurring near ∼500 km and ∼1000 km with near saturation amplitudes at very high altitudes (>1100 km).; The J0-ingress radio occultation of the Galileo orbiter by Jupiter exhibits a system of well defined, regularly spaced electron layers in the altitude range where the presence of gravity waves have been previously inferred. Based on the terrestrial analog of sporadic E and spread F ionospheric layers, it is argued that the observed layers are a result of dynamical processes rather than chemistry. The impact of upward propagating gravity waves on the plasma distribution in a H+ dominated ionosphere is studied as a possible forcing mechanism for the observed ionospheric structure. The relevant physics is discussed and illustrated with an analytic, small amplitude model. A time dependent, 2D, large amplitude model is developed to simulate the observed large excursions in the J0-electron density profile. It is demonstrated that gravity waves with parameters consistent with the thermal structure of Jupiter's upper atmosphere are capable of creating large peaks in the electron density similar to the observed ones. A wave driven plasma flux results in plasma removal above the altitude of maximum ionospheric response and plasma deposition in the region below, significantly modifying the initial steady state electron density profile. Various possible wave propagation scenarios and global implications are explored.