loading page

Multiproxy reconstructions of integral energy spectra for extreme solar particle events of 7176 BCE, 660 BCE, 775 CE and 994 CE
  • +1
  • Sergey A. Koldobskiy,
  • Florian Mekhaldi,
  • Ilya G. Usoskin,
  • Gennady A. Kovaltsov
Sergey A. Koldobskiy
University of Oulu

Corresponding Author:koldobsky.sergey@gmail.com

Author Profile
Florian Mekhaldi
Lund University
Author Profile
Ilya G. Usoskin
Space Physics and Astronomy Research Unit
Author Profile
Gennady A. Kovaltsov
Ioffe Physical-Technical Institute
Author Profile


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. Accordingly, CI measurements in natural 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.