Storm Enhanced Densities (SEDs) have been observed during major magnetic storms and have been strongly associated with sub-auroral polarization streams (SAPS). Much of the information that is available about these phenomena originates from observations with limited coverage in space or time. These data therefore cannot provide a complete picture of the phenomena nor address the underlying physics. This research project will attempt to model the SEDs and SAPS with a self-consistently coupled model of the inner magnetosphere and thermosphere-ionosphere-plasmasphere system in order to better understand the storm-time redistribution of plasmas in the ionosphere and plasmasphere. The coupled model used here includes all the storm-time drivers and simulates the subsequent response of the thermosphere, ionosphere, and plasmasphere. A particular noteworthy feature of the model is that it explicitly includes the interaction processes between the ring current and the ionosphere that produces the SAPS. The model includes a realistic magnetic field that will enable the longitudinal dependence of the ionospheric dynamics and electrodynamics to be addressed, in particular with regards to the question of whether the American longitude sector is unique. Three particular research topics to be pursued are: investigation of the plasma source of the SEDs, the altitude coupling of the SEDs and SAPS, and the interaction between reduced conductivities and the SAPS electric field. Extensive model validation against observations will be done, particularly for the gradients in total electron content, as well as comprehensive analysis of the electric fields and the global plasma transport responsible for producing SEDs. Five particular geomagnetic storms will be the focus of the investigation. These occurred from 2000 to 2005 and have been the subject of several publications. The broader impacts of the investigation include new insights into the response of the thermosphere and ionosphere to magnetic storms, a goal of the Space Weather Program, as well as improved understanding of magnetosphere-ionosphere coupling. The project may help lead to a predictive capability for gradients in total electron content which has important Space Weather applications such as for GPS and Wide Area Augmentation Systems (WAAS) used for navigation of commercial aircraft. The project is being led by a female scientist near the beginning of her research career.
