Date of Award

9-2025

Document Type

Thesis

Degree Name

Master of Science in Applied Physics

Department

Department of Engineering Physics

First Advisor

Kyle E. Fitch, PhD

Abstract

Predicting ionosphere effects on radio wave propagation is critical for communications and over-the-horizon radar systems. The D region is challenging to model for several reasons, one of which is chemical complexity. Ion density changes during sunrise/sunset introduce substantial uncertainty in electron density profiles (EDPs). The Data Driven D Region (D3R) model solves electron densities through an ion chemistry model and assimilates relevant space weather inputs. This study evaluates D3R against the Faraday International Reference Ionosphere (FIRI) and measurements using Very Low Frequency (VLF) propagation paths. Space weather event impacts on D3R EDPs are evaluated during the disturbed period from 8-12 May 2024. New chemistry involving oxygen species are introduced. Comparison of D3R to FIRI found that models agree during the day but differ at night. D3R partially agrees with VLF measurements. The inclusion of proposed chemistry produced O2(singlet) profiles which tentatively agree with literature and measurements. Interestingly, sunrise/sunset EDP asymmetry arose from proposed reactions, a feature noted in the literature. This research demonstrates the effectiveness of D3R during both quiescent and disturbed conditions and offers additional chemistry to improve model performance during sunrise/sunset periods.

AFIT Designator

AFIT-ENP-MS-25-S-005

Comments

An embargo was observed for posting this thesis.

Approved for public release. PA case number 88ABW 2025-0780.

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