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| Titel |
Signatures of cosmic-ray increase attributed to exceptional solar storms inferred from multiple cosmogenic radionuclide records |
| VerfasserIn |
Florian Mekhaldi, Raimund Muscheler, Florian Adolphi, Anders Svensson, Ala Aldahan, Göran Possnert, Joseph R. McConnell, Michael Sigl, Kees C. Welten, Thomas E. Woodruff |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100093
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| Publikation (Nr.) |
 EGU/EGU2014-15977.pdf |
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| Zusammenfassung |
| Miyake et al. (2012, 2013) discovered rapid increases of 14C content in tree rings dated to
AD 774-5 and AD 993-4 which they have attributed to cosmic-ray events. These extreme
particle events have no counterparts in the instrumental record and have been tentatively
associated with solar proton events, supernovae and short gamma-ray bursts, which have very
different energy spectra. Cosmogenic radionuclides such as 14C, 10Be and 36Cl arise from the
interaction of cosmic rays with atmospheric nitrogen, oxygen and argon. These radio-isotopes
are produced through different reaction pathways and vary with different energy
dependencies of the production rate cross section. Owing to this, yield functions can be
used to determine the energy level of incident particles. However, only 14C has
been measured at high resolution to quantify the energy and thus the origin of the
outbursts. We present an annually resolved record of 10Be from the NGRIP ice core for
the two events. In addition, we also utilized the GRIP ice core 36Cl record in our
analysis.
Our results show that the differential production of cosmogenic 14C, 10Be and 36Cl is
consistent with a solar energy spectrum. Considering the notable increase in radionuclides,
the solar storms would have had to be substantially greater than the largest recorded
geomagnetic storm, the so-called Carrington event. This challenges our understanding of the
sun’s dynamics. Furthermore, the events could possibly be of interest for the investigation of
potential cosmic ray-cloud linkages (Svensmark & Friis-Christensen, 1997). Alternatively,
such outbursts of energetic particles have the potential to deplete atmospheric ozone and alter
atmospheric circulation. Ultimately, the magnitude of such particle events draws attention to
the perhaps underestimated potential of the sun to cause great damage to modern
technologies.
References
Miyake, F., Masuda, K. & Nakamura, T. Another rapid event in the carbon-14
content of tree rings. Nature Communications 4:1748, DOI: 10.1038/ncomms2783
(2013).
Miyake, F., Nagaya, K., Masuda, K. & Nakamura, T. A signature of cosmic-ray increase
in AD 774–775 from tree rings in Japan. Nature 486, 240-242, DOI: 210.1038/nature11123
(2012).
Svensmark, H., & Friis-Christensen, E. Variation of cosmic ray flux and global cloud
coverage — A missing link in solar-climate relationships. J. Atmos. Sol., Terr. Phys., 59,
225–1232, DOI:10.1029/1998JD200091 (1997). |
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