Exospheric Studies and Geocoronal Applications

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This proposal outlines a three-year plan of research for (1) taking the final steps toward formulating and applying a path- integral approach to the collisional kinetics of the transition region between the thermosphere and exosphere, and (2) constructing geocoronal models with the goal for assessing the response of the exosphere to, and interaction with, thermospheric variations and magnetospheric processes. Throughout, the applications are geared toward observable or measurable quantities, based on the experience gained during the CHARM project that is currently winding down. The specific tasks making up this proposal are: o to complete the development of an algorithm for evaluating the kinetic distribution function of exospheric constituents in the transition zone between the exosphere and the collisionally-dominated thermosphere, and to incorporate this into realistic kinetic models of the hydrogen geocorona taking into account elastic collisions of atmomic H with O and He and charge-exchange collisions with H+ and O+ using realistic topside ionosphere models, o to carry out case studies of the interaction between the ring current and geocorona (beginning with quiet-time cases, using AMPTE-CCE -derived empirical models) to evaluate quantitatively the energetic particle flux onto the low- and mid-latitude thermosphere (and airglow emissions arising thereform), and in the case of storm-time ring current enhancements, to ascertain whether there is enough energy deposited into the thermosphere to affect the geocorona globally (i.e. to quantitatively investigated feedbacks), o to further develop a radiative transfer code to address non- isothermal thermospheres and to carry out unified analyses of Lyman and Balmer datasets collected over the last two decades, o to compile geocoronal models into a consistent reference set, and to use this set to determine values for parameters defined within a recently-developed analytic modeling scheme as functions of geophysical and solar indices, thereby providing workers in other areas of geospace research with a convenient representation of the geocorona, o and to continue the theoretical development of exospheres subject to non-gravitational forces to.