Author ORCID Identifier

https://orcid.org/0000-0002-9354-9734 

Date of Award

Spring 2026

Document Type

Thesis (Ph.D.)

Department or Program

Physics and Astronomy

First Advisor

Robyn Millan

Abstract

Electron microburst precipitation can be a significant and prevalent source of electron loss from Earth's radiation belts into the upper atmosphere. This precipitation has been of interest since its discovery in the 1960's, and the continued progression of experimental capabilities has allowed for new and comprehensive analysis to be conducted on this phenomenon. The \af{barrel} mission was able to remotely sense microburst precipitation in both Northern and Southern hemispheres. In this thesis, I have written an automated detection algorithm with which 38 microburst events (with each event containing tens to tens of thousands of individual microbursts) were detected in the \as{barrel} dataset. Once catalogued, these events were characterized in-depth; the large-scale occurrence and duration statistics of the events were determined, and the temporal properties of the individual microbursts were investigated. It is shown that a $\sim5$ s pulsation structure in the precipitation can evolve throughout the events, and was found to be present in all 38 events. Further, the meticulous characterization of the individual microburst properties and their evolution enabled the quantification of an additional, slowly-varying precipitation component in the microburst events. This component was also present in all 38 events. In this thesis, it is shown that the slowly-varying component represents the dominant source of electron precipitation potential during microburst events (as compared to the individual bursts). The relative properties of the smooth and burst components were also investigated. This work motivates further observation and theoretical work into the two-component nature of electron microburst precipitation as well as the time evolution of individual microburst properties.

Original Citation

K. Cantwell and R. Millan, “BARREL observations of microburst events with a slowly-varying component,” Geophysical Research Letters, vol. 51, no. 9, May 2024, DOI 10.1029/2023gl106277.

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