Committee: 

Dr. Cohen, Advisor       

Dr. Peterson, Chair

Dr. Anderson

Abstract: The objective of the proposed research is to develop a model of the D-region ionosphere’s electron density by leveraging both VLF transmitter and lightning driven remote sensing techniques. The D-region ionosphere (60−90 km in altitude) plays an important role in long-range and aviation communication systems, and it responds to space weather disturbances. Unfortunately, due to its altitude range, it is difficult to directly measure the D region’s electrical properties. The D region lies above the altitudes reachable by high-altitude balloons and below the altitudes reachable by satellites. Sounding rocket measurements are possible, and have been done in the past; however, they are costly and difficult to use on a large scale. Instead, very low frequency (VLF, 3−30 kHz) and low frequency (LF, 30−300 kHz) waves have been used to infer various properties of the D-region. Existing techniques have relied on either VLF transmitters or emissions from lightning, known as sferics, but never together in one model as the two are very different. VLF transmitters provide a steady and reliable, but narrow-frequency, signal, while sferics are chaotic and spatially random, but broadband. In this document, the current state of the art for both transmitter-based and sferic-based techniques is explored. Additionally, methods for unifying these two differing approaches are proposed.