Revision to Ice Core Volcanic Index 2 (IVI2)
From: Alan Robock <robock@xxxxxxxxxxxxxxxxxx>
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Dear Colleagues,
Due to feedback on our IVI2 datasets, we have reviewed and revised them. The automatic algorithm we used to align different ice core time series and produce the latitude and altitude distribution failed when the ice-core signal and the assigned time (year+month) of the eruption were out of alignment, and failed to add the 1167, 1227, and 1783 (Laki) eruptions to that file. So that file has been corrected. We thank Robert A. Rohde and Ivan Pechenezhskiy for pointing out this discrepancy to us and apologize for this error. But this correction is also part of the scientific process and shows once again that it is the best scientific practice to make your data freely available for others to use and to report back errors they find.
For the annual average time series, file IVI2 Total loading_501-2000Version2.txt has also been revised due to our review of our procedures: (NH = Northern Hemisphere, SH = Southern Hemisphere)
1. Data are only reported to two decimal places. Any more precision is illusory
2. The following changes, indicated by *** in the rightmost column are:
a. Year 933: Moved data for NH injection (and hence global injection) from year 939.
b. Year 991: SH signal moved to 992 so that it appears in the same year as the NH signal.
c. Year 993: NH signal moved to 992 so that it appears in the same year as the SH signal.
d. Year 1125: Very minor SH eruption removed.
e. Year 1194: SH signal moved to 1195 so that it appears in the same year as the NH signal.
f. Year 1196: NH signal moved to 1195 so that it appears in the same year as the SH signal.
g. Year 1963: The Agung loading has been reduced by about 20%, to be consistent with Gao et al. (2007).
h.
Year 1982: We added
El Chichón
using data from Sato et al. (1993), updated at http://data.giss.nasa.gov/modelforce/strataer/. Many of the ice cores we used
stopped before
this year, and we did not have enough ice core data to evaluate
this
eruption. Nevertheless, we
know what the
loading was from other data. We
previously
indicated this in the readme file, but want to put it in here to
make it easier for others to use the time series, keeping in mind
that these
are not ice core data.
The revised
data can be found at http://climate.envsci.rutgers.edu/IVI2/#Version2
Sincerely,
Alan Robock (robock@xxxxxxxxxxxxxxxxxx) and Chaochao Gao (gaocc@xxxxxxxxxx)
Reference: Gao, Chaochao, Luke Oman, Alan Robock, and Georgiy L. Stenchikov, 2007: Atmospheric volcanic loading derived from bipolar ice cores accounting for the spatial distribution of volcanic deposition. J. Geophys. Res., 112, D09109, doi:10.1029/2006JD007461. http://climate.envsci.rutgers.edu/pdf/GaoIceCores2006JD007461.pdf
-- Alan Robock, Professor II (Distinguished Professor) Editor, Reviews of Geophysics Director, Meteorology Undergraduate Program Associate Director, Center for Environmental Prediction Department of Environmental Sciences Phone: +1-848-932-5751 Rutgers University Fax: +1-732-932-8644 14 College Farm Road E-mail: robock@xxxxxxxxxxxxxxxxxx New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock
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