Energy in Earth's Magnetosphere
Creators: name: Brenner, Austin
Publisher: name: My University
Year: 2023
Subjects: subject: Solar wind magnetosphere coupling
subject: Energy transport in Earth's magnetosphere
subject: Magnetosphere magnetic reconnection
subject: Solar wind coupling function
subject: Poynting flux
subject: Magnetopause
subject: Aerospace Engineering
subject: FOS: Mechanical engineering
subject: Engineering

description: The space environment dominated by Earth’s magnetic field is the magnetosphere; this environment is carved from the surrounding solar wind, but under the right conditions the solar wind is able to directly interact with the planet. When this occurs, energy enters the magnetosphere system, which results in magnetic perturbations that can be hazardous for large infrastructure on the planet’s surface. This dissertation focuses on the large scale energy coupling processes between the solar wind and magnetosphere by using simulation tools. The first chapter provides motivation, introduction, and background, with brief history of magnetopsheric research. The second chapter outlines in detail the development of the methodology that is used throughout the rest of the work. The new magnetopause surface identification uses a state variable of magnetic topology combined with the plasma β∗ variable (representing the ratio of thermal and kinetic to magnetic pressure). These two variables combine to feed an isosurface detection algorithm which swiftly and consistently identifies the magnetopause surface, with superior coverage of the magnetosphere cusps compared with other methods. Chapters 3 is an analysis of a real storm event focusing first on energy transport at the magnetopause. The real event of February 2014 is analyzed, first with observations and empirical models, then with the new magnetopause detection of simulation output. It is found that the energy transport at the magnetopause is a balance of magnetic energy injection through the open topology lobes, and energy escape of thermal and kinetic energy through the closed topology region of the magnetopause. Additionally, it was determined that the magnetopause surface motion contributes significantly to net energy transport. Chapter 4 is a second real event study in which the magnetosphere is dissected, defining internal magnetospheric boundaries according to magnetic topology. Similar to chapter 3, the event is studied using observation and energy transport analysis of simulation output. For this work the magnetopause and magnetosphere interior are split by magnetic topology and day/night magnetic mapping. Two energy circulation paths are found. Externally energy enters through the open topology lobes, and exits through the closed topology magnetopause. Internally a recirculating energy pathway is uncovered sending magnetic energy from the dayside closed region back through the cusp to the lobes where it joins the injected energy from the solar wind, heading toward the nightside closed region in the tail. The results of chapter 4 fully quantify the classic Dungey cycle in terms of magnetosphere energy transport at Earth. Chapter 5 shows the preliminary results from a parameter study using 96 cases of two hour steady solar wind conditions. Strong internal magnetosphere energy dynamics are found, as evident by the significant changes in the total energy content of the magnetosphere, despite the input conditions being steady. This internal energy change makes it challenging to attribute the classic input-output style solar wind magnetosphere coupling function relationship. Chapter 6 concludes with an overview of the findings and contributions and outlines ongoing and future work. The major contributions are 1. magnetopause detection algorithms and energy analysis techniques, 2. improved understanding of magnetopause energy transport for real storm conditions, 3. quantification of the Dungey cycle, and 4. illustration of the complexity and challenges associated with attributing input-output coupling functions.