Study of the space weather effects during strong solar eruptions

This study is focused on developing and validating a robust methodology for analysing and estimating the risks associated with large solar eruptions. Namely, the research looks at the radiation impact at aviation altitudes caused by the arrival of large fluxes of charged particles created during strong eruptions, also known as solar energetic particles, at Earth. In instances where solar energetic particles possess enough energy they can be detected by ground-based detectors such as neutron monitors, we call these events ground-level enhancements. The energy and arrival direction of these particles at the Earth’s magnetosphere dictate where they are detected at the Earth’s surface. A key result of this thesis was the development of an open-source magnetospheric particle trajectory tracing tool, called OTSO, to replace out-of-date software. The development and validation of this tool were successful, providing a powerful tool for space weather risk analysis.
Solar energetic particles entering the atmosphere pose a radiation hazard to the aviation industry. Using neutron monitor data and OTSO, various ground-level enhancements were analysed. Results of the analysis were inputted into the radiation model CRAC:DOMO, updated as part of this work, to compute the radiation doses at aviation altitude caused by solar energetic particles. Comparisons with radiation measurements taken onboard flights during select ground-level enhancements were conducted and good agreement was achieved. Notably, the agreement between flights during the 2003 Halloween solar storm was excellent and validated the methodology developed in this work when applied to periods of extreme geomagnetospheric disturbance. This result provides much-needed insight into the radiation risks posed during strong geomagnetic storms allowing policymakers to consider some worst-case scenarios.
With the radiation risk assessment methodology validated and 21 ground-level enhancements analysed, aviation radiation doses were computed for all analysed events and a statistical analysis was conducted. A simple proxy for the radiation dose was found between neutron monitor count rate measurements and the computed aviation dose rate. This proxy can provide a useful tool for quick real-time radiation risk assessment by using neutron monitor data. Such a result can aid in the development of nowcasting tools and the mitigation of the radiation space weather impact caused during ground-level enhancements.