Effect of Interplanetary Shock Impact Angle on the Occurrence Rate and Properties of Pc5 Waves Observed by High-Latitude Ground Magnetometers

• Main Author: Baker, Andrew Ballard
• Other Authors: Electrical Engineering
• Format: Others
• Published: Virginia Tech 2019
• Subjects: Interplanetary Shocks; Ultra Low Frequency Waves; Pc5 Waves
• Online Access: http://hdl.handle.net/10919/90396

The effects of interplanetary shock impact angles have the potential to have far reaching consequences. By their nature, interplanetary shocks are a direct consequence of a variety of solar events including both Coronal Mass Ejections (CMEs) and Co-rotating Interaction Regions (CIRs). They have the ability to move the magnetopause, the boundary between the Earth's magnetosphere and the surrounding plasma, leading to ionospheric current systems and an enhanced ring current. Their association with a time-varying EMF also makes them potentially dangerous at a human level. This EMF can couple to electrical currents in technological infrastructure that can overload transformers, communication cables, and power grids. As IP shocks have the potential to have a large impact on our society, research to further our understanding of these events is prudent. We know that shocks can couple to currents and ULF waves in the magnetosphere-ionosphere system. Much of the current research into their behaviors has been focused on models and simulations and has indicated that the shock impact angle should affect the properties of the waves. To investigate the potential influence of the impact angle, data from a series of Antarctic magnetometers was collected and compared to a database of known interplanetary shocks to determine when the response to different shocks was detected at the magnetometer. For this investigation, we were concerned with determining what impact if any, the impact angle of the IP shock had on the generation of Pc5 waves. To that end, the power spectra both before and after the shock was calculated. This information was then combined with the shock impact angle to determine what effects if any, the shock impact angle had on Pc5 wave occurrence rates. From our research, it was determined that the impact angle of the interplanetary shock had a significant impact on the occurrence rate and properties of Pc5 waves observed by high-latitude ground magnetometers. === Master of Science === Interplanetary shocks, drive interactions between the solar wind and the Earth’s atmosphere, and they have the potential to have far reaching consequences. Caused by a variety of solar events including both Coronal Mass Ejections (CMEs) and Co-rotating Interaction Regions (CIRs), they have the ability to physically move the locations of regional boundaries of the ionized part of Earth’s atmosphere, leading to a variety of electromagnetic effects. They also pose a danger at the human level by generating electrical currents in technological infrastructure that can overload transformers, communication cables, and power grids. As they pose a danger to our society, understanding them is prudent. A large portion of the current research into their behaviors has been focused on models and simulations and has shown that the shock impact angle should affect the properties of the waves. For this investigation, data from a series of Antarctic sensors was collected and compared to a database of known interplanetary shocks to determine when different shocks were detected. Specifically, for our investigation, we were concerned with determining what impact if any, the impact angle of the IP shock had on the generation of Pc5 waves, a specific type of ULF wave. This was accomplished by calculating the power level at different frequencies both before and after the shock. This information was then combined with the shock impact angle to determine what effects if any, the shock impact angle had on Pc5 wave occurrence rates. From our research we found that the impact angle of the interplanetary shock had a significant impact on the generation of Pc5 waves.