Date of Award

Fall 2026

Abstract

This dissertation presents a systematic investigation of how the inclination of solar wind tangential discontinuities controls the dayside magnetospheric response using global MHD simulations conducted with the OpenGGCM model. This study is motivated by the need to understand how TD orientation controls dayside magnetospheric response, and adopts the view that the bow shock (BS) and magnetopause (MP) can be treated as large-scale discontinuities, such that their interaction with an interplanetary TD may be interpreted as a nonlinear discontinuity–discontinuity interaction. Within this framework, the role of TD orientation in governing the coupled evolution of disturbances across the dayside magnetospheric system is systematically investigated.

The results demonstrate that the system response proceeds through a sequence of coupled processes governed by TD orientation and the associated dynamic pressure enhancement. First, the interaction of a density-enhanced TD with the bow shock generates a cascade of secondary waves and discontinuities, including fast forward shocks. Second, these structures propagate through the magnetosheath, where they modify the plasma state and evolve into increasingly structured, spatially distributed disturbances as a function of TD orientation. Third, their interaction with the magnetopause constitutes a secondary discontinuity–discontinuity interaction, producing boundary deformation characterized by localized compression, oscillatory motion, and outward protrusions that may evolve into vortex-like structures. Increasing inclination drives a transition from a quasi-symmetric, wave-dominated response to an asymmetric regime dominated by TD draping, accompanied by increasingly complex dynamics.

These results indicate that magnetopause dynamics cannot be interpreted solely as a direct response to upstream pressure variations, but instead arise from nonlinear coupling between interacting discontinuities across the bow shock–magnetosheath–magnetopause system. This study provides a unified framework for solar wind–magnetosphere coupling in terms of discontinuity interactions and establishes a basis for interpreting in situ observations. Given the prevalence of TDs in the solar wind, their cumulative effects may contribute significantly to magnetospheric variability through repeated boundary interactions, emphasizing discontinuity-driven coupling beyond traditional drivers and its potential relevance to space weather variability.

Document Type

Dissertation

First Advisor

Joachim Prof. Raeder

Second Advisor

Lynn Prof. Kistler

Third Advisor

Antoinette Dr. Galvin

Department or Program

Physics

Degree Name

Doctor of Philosophy

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