The Variation of Radiation Effective Dose Rates and Single Event Effect Rates at Aviation Altitudes with Magnetospheric Conditions and Geographic Location

Abstract

The geographic structure of radiation dose rates at aircraft altitudes in Earth's atmosphere during the irradiation of Earth by proton spectra from incoming solar particle events is examined using the recently developed MAIRE+ software. Conditions are examined under two incoming proton spectra, a low/hard spectral index and a high/soft spectral index spectra, which are representative of some of the solar particle events that have caused reasonably sized Ground-Level Enhancements/Events (GLEs) over the past 70 years. It is found through the use of `cut-throughs' of the atmosphere, that the atmosphere can be divided into three volumes; a high dose rate polar region, a low dose rate equatorial region, and a transition region between the two. The location of these regions as a function of latitude, longitude and altitude is characterised. It is also found that the location of the transition region changes for different magnetospheric disturbance levels, implying that the total radiation dose rate an aircraft will experience if it passes through the transition region will be subject to large systematic uncertainties, particularly during the currently unknown levels of magnetospheric disturbance that a major solar event could cause. The impact that various magnetospheric conditions might have on dose rates that specific flight routes might experience is also discussed.