An Observational Study of Southern Hemisphere Poleward Moving Radar Auroral Forms Using 2021 SuperDARN Data

open_access
Open Access
Author:
Thayer, Aidan
Graduate Program:
Meteorology and Atmospheric Science
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 10, 2023
Committee Members:
William A Bristow, Thesis Advisor/Co-Advisor
Tim Kane, Committee Member
Paul Markowski, Program Head/Chair
Eugene Edmund Clothiaux, Committee Member
Keywords:
PMRAF
SuperDARN
Abstract:
Poleward Moving Radar Auroral Forms, or PMRAFs, are dense plasma forms that exist in the upper layer of our Earth’s atmosphere. They are known to cause problems with signal lock in satellite-to-ground communication paths and may cause increases in orbital drag for low-earth-orbiting satellites. Better understanding of PMRAF formation would allow for improvements in orbit prediction and better understanding of the energy balance in the magnetosphere-ionosphere coupled system. Currently, our understanding of the driving forces behind PMRAF formation has not advanced beyond the importance of the orientation of the component of interplanetary magnetic field parallel to the Earth’s magnetic field (IMF Bz) in the genesis of PMRAFs. This thesis examines the importance of the other interplanetary magnetic field parameters as well as the auroral indices AL and AU with basic statistics to parse their importance in PMRAF occurrence throughout 2021 at two stations in the Southern Hemisphere, specifically South Pole Station and McMurdo Station. It does so through the use of observations from the Super Dual Auroral Network, a series of high frequency, high latitude radars, that sends pulses which are scattered by the ionized plasma in the upper atmosphere. This thesis illustrates PMRAF behavior in three distinct case studies that cover more than 95% of the behavior observed from the 60 events documented throughout 2021. Three different data visualizations are used for these case studies - range time intensity plots, field of view plots, and convection maps. These three visualizations are explained in detail and examined for their respective signatures of PMRAFs in the case studies. This work finds that IMF By and AL potentially have an effect on PMRAF formation, though the uncertainty in mean occurrence frequencies is as large as their mean values.