Dissertation
Model-Based Properties of Earth's Protective Shield: Relating UT-based Dependencies of the Open/Closed Boundary, Cutoff Latitude, and L-Shell Parameter with Polar Cap Absorption Events
(2019)
Abstract
Though the technology is several decades old, high-frequency radio continues to be an important method of communication. Due to the nature of high-frequency radio propagation it is possible to transmit and receive signals over great distances. This has proven especially useful to the military, aviation, utility companies, etc.
High frequency radio is not without limitations. Sky waves are subject to varying ionospheric conditions, including radio wave absorption. Under certain conditions radio wave energy can be completely absorbed in the ionosphere. One specific absorption condition occurs in Earth's polar regions. So-called polar cap absorption events have been found to follow a well-defined pattern.
The polar cap region is defined by the open/closed boundary of the geomagnetic field. Polar cap absorption events are primarily caused by high-energy protons of solar origin between about 1-20 MeV.
There remain critical unanswered questions regarding polar cap absorption events: What is their dependence on solar wind parameters? What is their impact on radio communications? Are there variability sensitivities related to the open/closed boundary and other parameters impacting these events? One goal of this research was to answer some of these questions.
Using the Tsyganenko model of the geomagnetic field, several studies were completed, examining model-based properties of several key characteristics of the geomagnetic field such as the open/closed boundary, the cutoff latitude, the L-shell parameter, and the penumbra. Another goal of this research was to determine possible areas of improvement regarding current methods of forecasting polar cap absorption events.
Keywords
- Open/Closed Boundary,
- Polar Cap Absorption,
- Energy Cutoff Latitude,
- Energetic proton
Disciplines
Publication Date
Fall November 22, 2019
Degree
PhD
Field of study
Heliophysics and Aeronomy
Department
Physics
Advisors
Dr. Jan J. Sojka
Comments
This is the unfinished version of my PhD dissertation. It is still undergoing slight revisions. Page numbers in the Contents section may not match up. Thanks for your interest!
Citation Information
David Alan Smith. "Model-Based Properties of Earth's Protective Shield: Relating UT-based Dependencies of the Open/Closed Boundary, Cutoff Latitude, and L-Shell Parameter with Polar Cap Absorption Events" (2019) Available at: http://works.bepress.com/david-smith/18/
Creative Commons license
This work is licensed under a Creative Commons CC_BY International License.