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Evidence for an 1859/1860 nitrate spike in the Greenland ice sheet
C. M. Laird1, G. A. M. Dreschhoff1, T. P. Armstrong1, 2, A. L. Melott1, andB. C. Thomas1, 3
1. Department of Physics and Astronomy, University of Kansas, Lawrence, KS 660452. Fundamental Technologies, LLC, Lawrence, KS 66046 3. Department of Physics and Astronomy, Washburn University, Topeka, KS 66621
A reanalysis of the GISP2 H ice core ECM (Electrical Conductivity Method) and nitrate data around the NO3
- spike previously dated to late 1859 suggests the feature most likely appears in early 1860.
Utilized standard method for absolute dating of ice cores:1. ECM (volcanism) – establishes marker years 1853, 1854, 1883,… 2. proxies exhibiting annual cycles (e.g. nitrates) - count/interpolate
years between markers 3. combining 1. and 2. gives annual dating
=> Nitrate spike most probably occurs in 1860.
Dating Methodology – GISP2 H CoreDreschhoff and Zeller, 1994
1859 or 1860one or two years
GISP2 H Core Segment - Dreschhoff and Zeller, 1994 (evenly-spaced samples)
1. Shiveluch (1854) and Krakatau (1883) ECM markers bracket nitrate spike2. annual nitrate cycles count/interpolate years between markers3. 1. & 2. => NO3
- spike most probably occurs in 1860 (not 1862/1863)
ECMNO3
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