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Multiradionuclide evidence for an extreme solar proton event around 2,610 B.P. (∼660 BC)

  • Paschal O’Hare
  • Florian Mekhaldi
  • Florian Adolphi
  • Grant Raisbeck
  • Ala Aldahan
  • Emma Anderberg
  • Jürg Beer
  • Marcus Christl
  • Simon Fahrni
  • Hans Arno Synal
  • Junghun Park
  • Göran Possnert
  • John Southon
  • Edouard Bard
  • Raimund Muscheler
Publishing year: 2019
Language: English
Pages: 5961-5966
Publication/Series: Proceedings of the National Academy of Sciences of the United States of America
Volume: 116
Issue: 13
Document type: Journal article
Publisher: National Acad Sciences

Abstract english

Recently, it has been confirmed that extreme solar proton events can lead to significantly increased atmospheric production rates of cosmogenic radionuclides. Evidence of such events is recorded in annually resolved natural archives, such as tree rings [carbon-14 (
C)] and ice cores [beryllium-10 (
Be), chlorine-36 (
Cl)]. Here, we show evidence for an extreme solar event around 2,610 years B.P. (∼660 BC) based on high-resolution
Be data from two Greenland ice cores. Our conclusions are supported by modeled
C production rates for the same period. Using existing
Cl ice core data in conjunction with
Be, we further show that this solar event was characterized by a very hard energy spectrum. These results indicate that the 2,610-years B.P. event was an order of magnitude stronger than any solar event recorded during the instrumental period and comparable with the solar proton event of AD 774/ 775, the largest solar event known to date. The results illustrate the importance of multiple ice core radionuclide measurements for the reliable identification of short-term production rate increases and the assessment of their origins.


  • Geosciences, Multidisciplinary
  • Ice cores
  • Radionuclides
  • Solar proton events
  • Solar storms


  • ISSN: 0027-8424
Florian Adolphi
E-mail: florian [dot] adolphi [at] geol [dot] lu [dot] se

Postdoctoral fellow

Quaternary Sciences

+46 46 222 42 67

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