SM51D-4270:
Thermospheric Wind Impacts on Ionospheric Upflow and Outflow

Friday, 19 December 2014
Meghan Burleigh, Embry-Riddle Aeronautical University, Daytona Beach, FL, United States and Matthew D Zettergren, Embry-Riddle Aeronautical Univ, Daytona Beach, FL, United States
Abstract:
Significant amounts of thermal ionospheric plasma can be transported to high altitudes in response to magnetospheric and atmospheric forcing. Soft electron precipitation serves as a heat source for the ambient F-region ionospheric electrons, which enhances the ambipolar electric field and induces upflowing ions. Frictional heating of ions from fast convection through the neutral atmosphere creates pressure-driven ion upflows. Finally, large neutral winds along the geomagnetic field may effectively lift or lower the F-region density peak. At regions above where ion upflows are typically initiated, transverse ion acceleration is thought to give upflowing ions sufficient energy to escape to the magnetosphere.

This study examines how low-altitude upflow processes affect ion outflow, focusing particularly on the impacts of neutral winds. A new multi-fluid ionospheric model, which solves conservation equations for mass, momentum, and parallel and perpendicular energy is developed for this study. These fluid equations are solved for all species relevant to the E, F, and topside ionospheric regions and the system is closed through an electrostatic treatment of the auroral currents. This model is driven by the specification of field-aligned currents and a resonant transverse heating term. The model therefore encapsulates the basic ionospheric upflow processes and provides a simple way to approximate the effects of transverse heating and ion outflow. Using this model, individual species responses to electron precipitation, frictional heating, neutral winds, and transverse heating are examined to determine the effects of these low-altitude upflow processes on ion outflow. Results suggest that upflows, including those induced by neutral winds, can have a significant impact on the types and amounts of outflowing ions.
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