Abstract Radiation from space in the form of galactic cosmic rays (GCRs) generates a persistent background of ionizing radiation in Earth's atmosphere. The dose rate of ionizing radiation due to GCRs increases from sea level to aviation altitudes. The Nowcast of Aerospace Ionizing RAdiation System (NAIRAS) model is a state‐of‐the‐art model for predicting radiation dose rates at aviation altitudes and is used to limit doses to aircrew and passengers. However, dosimetry data from the Automated Radiation Measurements for Aerospace Safety (ARMAS) system flown on commercial aircraft have revealed dose rates at aviation altitudes greater than predicted by NAIRAS. One theory, supported by correlation analyses, posits that these so‐called excess dose rates are caused by relativistic electron precipitation (REP) driven by hiss waves in the inner magnetosphere. In this work, we use a validated Monte Carlo model of particle transport through the atmosphere in combination with GCR measurements from low Earth orbit (LEO) to attempt to explain the ARMAS dose rate measurements with GCRs alone. We find that our predicted GCR dose rates are in statistical agreement with the ARMAS data, but still underestimate the dose rates for some events. We then simulate REP using electron measurements from LEO and find that REP can only explain up to about of the difference between GCR dose rates and ARMAS data in the most extreme cases. With support from previous literature, we conclude that REP is unlikely to be the source of the discrepancies between GCR dose rate predictions and ARMAS measurements.
Claxton et al. (Mon,) studied this question.