Semester

Summer

Date of Graduation

2014

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Physics and Astronomy

Committee Chair

Amy M. Keesee

Committee Co-Chair

Loren Anderson

Committee Member

Paul A. Cassak

Committee Member

John Christian

Committee Member

Earl E. Scime.

Abstract

Earth's magnetosphere is an inherently complex, strongly nonlinear system with intrinsic coupling between internal and external drivers. In general, magnetospheric systems can be understood as a balance between multiple regions which all exhibit unique plasma properties. The feedback processes between each region depend on geomagnetic activity levels and the preceding states of the solar wind and the respective magnetospheric regions. Of particular interest is understanding how ion temperatures evolve during geomagnetically active periods, and also understanding the space weather impacts of hot ion populations injected during such periods. Dynamic, spatiotemporally resolved ion temperature boundary conditions have been implemented into the Comprehensive Ring Current Model (CRCM); the temperatures are based on 2-D equatorial maps derived from remotely imaged energetic neutral atom (ENA) measurements. The high-speed-stream-driven event on 22 July 2009 and the coronal mass ejection-driven event on 30-31 October 2013 are simulated and compared against identical simulations using a statistically derived boundary condition model.;This new method for establishing boundary conditions allows users to include event-specific observations associated with a dynamic plasma sheet. It is found that spatial and energy distributions in the storm-time ring current exhibit sensitive dependence on boundary conditions during these events. The coupling of boundary conditions to the time history of the convection electric field strength is found to play an important role in throttling the influence of the boundary plasma on the inner magnetosphere. Storm-time dusk-dawn asymmetries consistent with observational data are reproduced well when CRCM is provided with the event-specific boundary condition model. The dependence of average, global magnetospheric ion temperatures derived from ENA maps is also investigated as a function of various combinations of solar wind parameters, IMF parameters, and geomagnetic indices. Covering a 31-month interval of time near solar maximum, the parametric study reveals average stormtime features consistent with various in situ observations, ionospheric observations, and ground-based measurements.

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