CAREER: Quantification of Ionosphere/Thermosphere System Drivers, State Parameters, and Fundamental Coupling Mechanisms

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The goal of this project is to obtain the first unambiguous quantification of the temperature-dependent cross section for charge exchange between neutral and ionized atomic oxygen which mediates momentum and energy exchange between the terrestrial ionosphere and thermosphere (IT system). Historical uncertainty in these parameters has limited the quantitative accuracy of numerous aeronomical calculations, such as ionospheric temperatures and density distributions, diffusion coefficients, and plasma drift speeds, effectively precluding reliable prediction of both steady-state and dynamic behavior of the coupled IT system. The research program will involve hardware development and deployment, inverse and tomographic analysis development, physics-based model development, and scientific data analysis and interpretation. The methodology to obtain the crucial quantification of these parameters will utilize a nested configuration of passive optical and incoherent scatter radar (ISR) instrumentation at Arecibo Observatory in Puerto Rico, including a novel photometric imaging system (Photometer Array for Tomographic Hydrogen Sensing; PATHS) that will be designed and built by undergraduate students at the University of Illinois through a capstone project course. The resulting data, together with the development of realistic radiative transport models of optical emissions and advances in the estimation of light ion velocity from ISR spectra, will enable the height- and time-dependent quantification of neutral, ion, and electron temperatures; distinct proton and oxygen ion velocities; neutral meridional wind speed; ionized oxygen, hydrogen, and helium density; and, for the first time, the neutral oxygen and hydrogen density distributions throughout the upper thermosphere. Quantification of the charge exchange coupling between the ionosphere and thermosphere (via parametric momentum balance) as well as between the exosphere and plasmasphere (via parametric continuity balance) will enable advances in understanding how mass, energy and momentum are transported throughout the coupled regions. The project will involve graduate and undergraduate students, and include outreach activities targeting pre-college girls in order to promote the future gender diversity in this discipline.