Date of Award
8-2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Physics and Astronomy
Committee Chair/Advisor
Stephen Kaeppler
Committee Member
Gerald Lehmacher
Committee Member
Joan Marler
Committee Member
Jens Oberheide
Abstract
Have you ever been driving down the road around noon, turned on the radio to an AM station and got mostly static breaking up your news, or only pick up stations close to you? Have you ever been driving down the same road around midnight, turned on the radio to the same station, and heard the music come in clearly, with no static at all, or been able to pick up stations 100s of miles away? Well, this is all due to the region of the Earth’s upper atmosphere, known as the ionosphere. Most of Earth’s atmosphere is considered neutral; however, the ionosphere is the charged portion that allows the propagation of HighFrequency (HF) radio waves. The standard flow of the ionosphere follows the sun, i.e., as the sun rises, the ionosphere becomes more ionized, peaking when the sun is at its highest point, and then, as the sun sets, the ionization of the ionosphere drops off very quickly. This process allows HF signals to travel much farther at night than during the day, as radio waves bounce off of the ionized regions. Although other forms of communication exist today, they all rely on man-made infrastructure. Therefore, when that is no longer accessible, other forms of emergency broadcasting are crucial. That is why radio communication is still widely accepted as the most reliable method of long-distance communication, as it does not require any man-made infrastructure. So, without the ionosphere, we would have no way to communicate over long distances. Several natural phenomena can alter the ionization levels in the ionosphere. These events can then alter the propagation of radio signals, which can affect the ability of the signals to then be detected. In turn, this jeopardizes the potential spread of information. This work uses a signal of opportunity within the bandwidth of standard emergency broadcasts to study these disturbances as they move across the Eastern United States. We also highlight a less well-documented structure that we believe needs to be accounted for when discussing these disturbances.
Recommended Citation
Markowski, Danielle, "Day-to-Day Ionospheric Variability in the Midlatitudes" (2026). All Dissertations. 4353.
https://open.clemson.edu/all_dissertations/4353