Date of Award:

5-2015

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Physics

Committee Chair(s)

Jan J. Sojka

Committee

Jan J. Sojka

Committee

Charles G. Torre

Committee

Bela G. Fejer

Committee

Ludger Scherliess

Committee

Anthony R. Lowry

Abstract

This research investigated how electric fields, currents, and charged particles in Earth's high-latitude ionosphere respond to changing input from the sun. The ionosphere surrounds the entire Earth, makes radio communication possible, and can significantly degrade satellite communications and geo-positioning (navigation) capabilities. Many satellites fly within the ionosphere where a solar storm can cause increased satellite drag or destroy onboard electronics. Therefore, understanding and correctly predicting the behavior of this environment is important, and the results from this research will be used to improve current ionospheric models.

A relationship between the level of magnetic activity on Earth due to changes in the solar wind on and the response of Earth's high-latitude ionosphere was determined by examining ion and electron flow patterns in the polar cap and auroral regions. The data was obtained from a sun-synchronous polar-orbiting Defense Meteorological Satellite Program (DMSP) satellite during a time of quiet solar activity. Using this data, averaged patterns of the high-latitude ion and electron flow were created to examine the behavior of the polar cap. For very low geomagnetic activity, the polar cap radius was found to be five degrees smaller than the polar cap radius currently used in simple ionospheric models.

Additionally, each orbit was considered individually to obtain an analytic representation of the velocity profile. This was done separately in both the dawn and dusk regions to study how the rapidly decreasing ion and electron flows are related to the geomagnetic activity. A much larger than expected asymmetry was found between the dusk and dawn sectors with the dawn sector flows decreasing twice as fast as the dusk sector flows.

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