Committee: 

Dr. Cohen, Advisor       

Dr. Scott, Chair

Dr. Durgin

Abstract:

The objective of the proposed research is to: 1) determine the correlation length scale of the D-region, 2) determine the root-mean-squared (RMS) height variation of reflections, 3) perform a statistical analysis of the selected metrics, and 4) model the results or incorporate aspects of roughness into an existing model. The D-region of the ionosphere, which ranges from about 60-100 km, is too high for continuous in-situ measurements, such as with high-altitude balloons, and too low for satellite-based measurements. As such, its properties remain largely unknown compared to other layers of the atmosphere and near-Earth space environment. The bulk of research studying the D-region utilizes Very Low Frequency (VLF) waves, which propagate efficiently to global distances. These waves, however, make it difficult to study a very localized region of the ionosphere, thus little is known about D-region scattering on a scale less than ~10-100 km. As an alternative, Low Frequency (LF) and Medium Frequency (MF) waves could be used as a diagnostic tool of the D-region. These higher frequencies have a higher attenuation rate than VLF, but this allows only a few modes to propagate, thus greatly simplifying the propagation problem to solve. The purpose of this research is to leverage LF/MF signals to study the small-scale scattering, i.e. the "roughness", of the D-region.