Date of Award

Spring 1-1-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Aerospace Engineering Sciences

First Advisor

Scott E. Palo

Second Advisor

Marcin Pilinski

Third Advisor

Jeffrey Thayer

Fourth Advisor

Delores Knipp

Fifth Advisor

Kristine Larson

Abstract

A reduction in Arctic sea ice extent is driving an increase in Arctic Circle ship traffc and a requirement for communications in the region. High-latitude ionospheric behavior can significantly impact Ultra High Frequency (UHF) transmissions including degradation of Global Positioning System (GPS) position solutions. To address these operational concerns, a need arises to identify and understand the ionospheric structures that lead to disturbed conditions in Arctic latitudes. This research focuses on determining those structures that occur within the Alaskan high-latitude sector, and comparing their local relative importance to that across the broader northern high-latitudes. The goal is to identify correlative features between GPS scintillation, electron densities and their gradients, as seen by ground GPS receivers in Alaska and the Poker Flat Incoherent Scatter Radar (PFISR), as well as other instruments and models available for context.

Several case studies are examined, specifically global and local geomagnetically disturbed times that allow for the isolation of ionospheric sources associated with GPS scintillation. Upon determination of known scintillating E and F region structures, the relative importance of each is compared in terms of the frequency, duration, and extent of operational impact. These results are compared across the broader high-latitude region to gain insight into the timing and location of physical mechanisms that drive GPS scintillations in the Arctic. Analysis indicates that E region auroral activity is the primary driver in Alaska. This differs from the Arctic European sector where F region auroral blobs structured by precipitating particles have been reported as the primary causal structures. Geomagnetic conditions vary greatly across the Arctic, so differences between sectors is not surprising. While further modeling and studies are required to understand why the differences exist, the observed differences themselves give observational insight into potential causes. The uniqueness of this work lies in the use of a predictive conjunction analysis between the PFISR beam array and known GPS satellite signal paths to determine experiment times and both single and multi-beam experiment configurations. This is coupled with all sky imagery for broader contextual interpretation; and, the approach can be transitioned to future work conducted across other high-latitude sectors.

Available for download on Monday, October 28, 2019

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