Graduation Semester and Year
Summer 2025
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Physics and Applied Physics
Department
Physics
First Advisor
Ramon Lopez
Second Advisor
Yue Deng
Third Advisor
Cheng Sheng
Fourth Advisor
Zihan Wang
Fifth Advisor
Amir Shahmoradi
Abstract
As humanity's technological dependence grows, so does its vulnerability to space weather. Space weather describes solar-driven phenomena in the near-Earth space environment and their terrestrial effects. Many of these effects occur due to the interaction of the solar wind and Earth's magnetosphere. The solar wind originates at the solar corona and carries solar plasma and magnetic field outward through the solar system. This magnetic field, known as the interplanetary magnetic field (IMF) during transit, can undergo magnetic reconnection with Earth's geomagnetic field when oppositely aligned field lines converge. This process transfers energy into Earth's magnetosphere, driving space weather phenomena.
Space weather events pose significant risks to modern technology. Radio blackouts can disrupt communication, while ionospheric scintillation can affect navigation and positioning systems. Geomagnetically induced currents, generated when rapidly fluctuating magnetic fields induce currents in long conductors such as pipelines and power lines, can damage critical infrastructure. In space, satellite drag from thermospheric heating can lead to destabilized satellite orbits. To understand and predict these phenomena, magnetohydrodynamic (MHD) models have been developed and transitioned from research tools to operational forecasting models at agencies such as the Space Weather Prediction Center (SWPC) in a process referred to as research-to-operations.
Despite advances in space weather modeling, uncertainties in predictive model outputs remain yet to be fully understood. The extent to which different model parameters contribute to overall error has not been thoroughly characterized. One potential error source is the quality of input data used to drive these models. Space weather models typically rely on solar wind data defined at the model’s upstream boundary as input conditions. For forecasting and nowcasting, this data typically comes from upstream measurements projected to near-Earth space, most commonly through the NASA Space Physics Data Facility (SPDF) OMNI data service. OMNI provides continuous solar wind coverage from the L1 Lagrange point, propagated downstream to Earth's bow shock nose using measurements from three satellites: ACE, Wind, and DSCOVR. While OMNI represents the current best capability for continuous near-Earth solar wind coverage, propagation errors can result in model inputs that do not faithfully reflect the true solar wind arriving at Earth, leading to inaccurate model outputs which do not accurately reflect reality.
This study quantifies OMNI's reliability in propagating solar wind from L1 to Earth's bow shock nose under varying conditions. We examine three categories: "quiet-time" solar wind (typical conditions that do not drive geomagnetic storms), coronal mass ejections (CMEs), and high-speed streams (HSSs), of which the latter two are both storm-driving phenomena. We examine OMNI's propagation accuracy by comparing predicted solar wind at Earth with data from the near-Earth ARTEMIS satellite during intervals when the spacecraft was on the day side near the Earth-Sun line. Additionally, we examine how ionosphere-thermosphere model outputs respond at the grid cell level to varying accuracy in the predicted quiet-time solar wind. Our results show that CMEs are typically well-predicted at Earth, HSSs are poorly predicted, and quiet-time solar wind falls between these extremes. Notably, higher OMNI propagation accuracy does not always correspond to more realistic model outputs. These findings have important implications for space weather forecasting, particularly for satellite drag estimations using upstream solar wind-driven models.
Keywords
Space Weather, Space Physics, Solar Wind, Heliophysics, Magnetosphere, IMF, CME, HSS
Disciplines
Other Physics | The Sun and the Solar System
License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 International License.
Recommended Citation
Fredrick, Espen T., "Uncertainty in Solar Wind Propagation: An Analysis of L1 to Earth Variability and the Implications for Geospace Modeling in Space Weather Operations" (2025). Physics Dissertations. 181.
https://mavmatrix.uta.edu/physics_dissertations/181