Solar cosmic ray events for the period 1561-1994: 1. Identification in polar ice, 1561-1950

The geophysical significance of the thin nitrate‐rich layers that have been found in both Arctic and Antarctic firn and ice cores, dating from the period 1561–1991, is examined in detail. It is shown that variations of meteorological origin dominate the record until the snow has consolidated to high...

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Bibliographic Details
Published in:Journal of Geophysical Research: Space Physics 2001-10, Vol.106 (A10), p.21585-21598
Main Authors: McCracken, K. G., Dreschhoff, G. A. M., Zeller, E. J., Smart, D. F., Shea, M. A.
Format: Article
Language:English
Subjects:
Astronomy
Earth, ocean, space
Exact sciences and technology
External geophysics
Particle radiation, solar wind
Snow. Ice. Glaciers
Solar physics
Solar system
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Summary:The geophysical significance of the thin nitrate‐rich layers that have been found in both Arctic and Antarctic firn and ice cores, dating from the period 1561–1991, is examined in detail. It is shown that variations of meteorological origin dominate the record until the snow has consolidated to high‐density firn some 30 years after deposition. The thin nitrate layers have a characteristic short timescale (30 MeV solar proton events having an omnidirectional fluence exceeding 6 × 109 cm−2. It is concluded that the impulsive nitrate events are reliable indicators of the occurrence of large fluence solar proton events and that they provide a quantitative measure of these events. It is further concluded that the impulsive nitrate events will permit the study of solar activity for many thousands of years into the past.
ISSN:0148-0227
2156-2202
DOI:10.1029/2000JA000237