University of Oulu

Koldobskiy, S., Mekhaldi, F., Kovaltsov, G., & Usoskin, I. (2023). Multiproxy reconstructions of integral energy spectra for extreme solar particle events of 7176 BCE, 660 BCE, 775 CE, and 994 CE. Journal of Geophysical Research: Space Physics, 128, e2022JA031186.

Multiproxy reconstructions of integral energy spectra for extreme solar particle events of 7176 BCE, 660 BCE, 775 CE, and 994 CE

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Author: Koldobskiy, Sergey1; Mekhaldi, Florian2,3; Kovaltsov, Gennady4;
Organizations: 1Space Physics and Astronomy Research Unit and Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland
2Department of Geology-Quaternary Sciences, Lund University, Lund, Sweden
3British Antarctic Survey, Ice Dynamics and Paleoclimate, Cambridge, UK
4Ioffe Physical-Technical Institute RAS, St. Petersburg, Russia
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.4 MB)
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Language: English
Published: American Geophysical Union, 2023
Publish Date: 2023-08-28


Extreme solar particle events (ESPEs) are rare and the most potent known processes of solar eruptive activity. During ESPEs, a vast amount of cosmogenic isotopes (CIs) 10Be, 36Cl, and 14C can be produced in the Earth‘s atmosphere and deposited in natural stratified archives. Accordingly, CI measurements in these archives allow us to evaluate particle fluxes during ESPEs. In this work, we present a new method of ESPE fluence (integral flux) reconstruction based on state-of-the-art modeling advances, allowing to fit together different CI data within one model. We represent the ESPE fluence as an ensemble of scaled fluence reconstructions for ground-level enhancement (GLE) events registered by the neutron monitor network since 1956 coupled with satellite and ionospheric measurements data. Reconstructed ESPE fluences appear softer in its spectral shape than earlier estimates, leading to significantly higher estimates of the low-energy (E < 100 MeV) fluence. This makes ESPEs even more dangerous for modern technological systems than previously believed. Reconstructed ESPE fluences are fitted with a modified Band function, which eases the use of obtained results in different applications.

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Series: Journal of geophysical research. Space physics
ISSN: 2169-9380
ISSN-E: 2169-9402
ISSN-L: 2169-9380
Volume: 128
Issue: 3
Article number: e2022JA031186
DOI: 10.1029/2022ja031186
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
1171 Geosciences
Funding: This work was partly supported by the Academy of Finland (Projects ESPERA 321882 and QUASARE 330064), University of Oulu (Project SARPEDON). F. Mekhaldi acknowledges funding from the Swedish Research Council (2020-00420), and the Royal Physiographic Society of Lund.
Academy of Finland Grant Number: 321882
Detailed Information: 321882 (Academy of Finland Funding decision)
330064 (Academy of Finland Funding decision)
Copyright information: © 2023. American Geophysical Union. All Rights Reserved.