Date of Award

5-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

Committee Chair/Advisor

Dr. Stephen Kaeppler

Committee Member

Dr. Gerald Lehmacher

Committee Member

Dr. Xian Lu

Committee Member

Dr. Jonathan Zrake

Abstract

Joule heating results from the collisional interaction between ions and neutrals and serves as a crucial mechanism for energy transfer between Earth's magnetosphere and ionosphere-thermosphere system, particularly at high latitudes. This dissertation investigates the modulation of Joule heating by altitude-resolved neutral winds, electric fields, and conductivity variations through multi-instrument observational analysis and modeling that incorporates both in-situ and ground-based sources to measure the main drivers of ion-neutral coupling. The observations presented consistently demonstrate a dual regulatory effect of the neutral wind on energy deposition that varies systematically with both geomagnetic activity level and proximity to auroral boundaries. In regions characterized by low geomagnetic activity and poleward of auroral arcs, neutral winds enhance Joule heating and significantly contribute to ion-neutral coupling during quiescent conditions. Conversely, in regions near auroral arc boundaries or during elevated geomagnetic activity, neutral winds systematically inhibit frictional heating and function effectively as a regulator of energy deposition. Overall, the inclusion of neutral winds is shown to alter heating estimates on average by as much as 40% depending on the particular regime, which emphasizes its critical role in this energy dissipation mechanism. The altitude-dependent interactions are also investigated that both confirms previous literature while providing new insights into the nuanced role of neutral winds within this complex form of energy exchange.

Author ORCID Identifier

0000-0002-5679-7421

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