Date of Award

Spring 2018

Project Type

Dissertation

Program or Major

Physics

Degree Name

Doctor of Philosophy

First Advisor

Marc R Lessard

Second Advisor

Roy Torbert

Third Advisor

Lynn Kistler

Abstract

Fine-scale structure plays an important role in the ionosphere and can be used to learn new information about a whole host of phenomena. This dissertation presents three separate studies of fine-scale ionospheric phenomena. First, morphological behavior of black aurora with pulsating aurora provides new information on how pulsating aurora interacts with the ionosphere. Black curls in conjunction with pulsating aurora indicate diverging electric fields in and above the ionosphere, which is visual evidence that black aurora is part of an ionospheric feedback mechanism. Next, a year of magnetometer observations in the extremely-low frequency (ELF) range placed new physical constraints on the conditions necessary for detecting narrow bandwidth, whistler-like spectral features. Solar zenith angle at the time of detection illustrated the dependence of ELF whistlers on a sunlit ionosphere. Sources of free energy in the ionosphere like solar photoionization may generate instabilities in the ionosphere that produce the fine-scale spectral features. Finally, results from the RENU 2 sounding rocket are analyzed to investigate fine-scale, anomalous density structures in the high latitude ionosphere. Observations from an ultraviolet detector indicate significant levels of small scale structuring. Supporting observations from orbital spacecraft supplement the study with a new technique for two-dimensional tomographic reconstructions of photon emission in the region. Analysis of multiple measurements in the thermosphere provides an unprecedented view of fine structure at high latitudes.

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