University of Oulu

Mishev, A., Panovska, S., & Usoskin, I. (2023). Assessment of the radiation risk at flight altitudes for an extreme solar particle storm of 774 AD. Journal of Space Weather and Space Climate, 13, 22.

Assessment of the radiation risk at flight altitudes for an extreme solar particle storm of 774 AD

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Author: Mishev, Alexander1,2; Panovska, Sanja3; Usoskin, Ilya1,2
Organizations: 1Space Physics and Astronomy Research Unit, University of Oulu, Pentti Kaiteran katu 1, 90570 Oulu, Finland
2Sodankylä Geophysical Observatory, University of Oulu, Tähteläntie 62, 99600 Sodankylä, Finland
3GFZ German Research Centre for Geosciences, Helmholtz Centre Potsdam, Wissenschaftpark “Albert Einstein”, Telegrafenberg, 14473 Potsdam, Germany
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.6 MB)
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Language: English
Published: EDP Sciences, 2023
Publish Date: 2023-09-26


Intense solar activity can lead to an acceleration of solar energetic particles and accordingly increase in the complex radiation field at commercial aviation flight altitudes. We considered here the strongest ever reported event, namely that of 774 AD registered on the basis of cosmogenic-isotope measurements, and computed the ambient dose at aviation altitude(s). Since the spectrum of solar protons during the 774 AD event cannot be directly obtained, as a first step, we derived the spectra of the solar protons during the ground level enhancement (GLE) #5 on 23 February 1956, the strongest event observed by direct measurements, which was subsequently scaled to the size of the 774 AD event and eventually used as input to the corresponding radiation model. The GLE #5 was considered a conservative approach because it revealed the hardest-ever derived energy spectrum. The global map of the ambient dose was computed under realistic data-based reconstruction of the geomagnetic field during the 774 AD epoch, based on paleomagnetic measurements. A realistic approach on the basis of a GLE #45 on 24 October 1989 was also considered, that is by scaling an event with softer spectra and lower particle fluxes compared to the GLE #5. The altitude dependence of the event-integrated dose at altitudes from 30 kft to 50 kft (9.1–15.2 km) was also computed for both scenarios. Our study of the radiation effects during the extreme event of 774 AD gives the necessary basis to be used as a reference to assess the worst-case scenario for a specific threat, that is radiation dose at flight altitudes.

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Series: Journal of space weather and space climate
ISSN: 2115-7251
ISSN-E: 2115-7251
ISSN-L: 2115-7251
Volume: 13
Article number: 22
DOI: 10.1051/swsc/2023020
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: Part of this work was supported by the Academy of Finland (project 330063 QUASARE and 321882 ESPERA). The work was also supported by the HE program, project ALBATROS. This work was partially supported by the National Science Fund of Bulgaria under contract KP-06-H28/4. S. Panovska acknowledges the Discovery Fellowship at the GFZ Potsdam, Germany.
Academy of Finland Grant Number: 330063
Detailed Information: 330063 (Academy of Finland Funding decision)
321882 (Academy of Finland Funding decision)
Copyright information: © A. Mishev et al., Published by EDP Sciences 2023. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.