  We have compared the yearly production rates of 10Be by cosmic rays in the
Earths polar atmosphere over the last 50-70 years with 10Be measurements from
two separate ice cores in Greenland. These ice cores provide measurements of
the annual 10Be concentration and 10Be flux levels during this time. The
scatter in the ice core yearly data vs. the production data is larger than the
average solar 11 year production variations that are being measured. The cross
correlation coefficients between the yearly 10Be production and the ice core
10Be measurements for this time period are <0.4 in all comparisons between ice
core data and 10Be production, including 10Be concentrations, 10Be fluxes and
in comparing the two separate ice core measurements. In fact, the cross
correlation between the two ice core measurements, which should be measuring
the same source, is the lowest of all, only ~0.2. These values for the
correlation coefficient are all indicative of a "poor" correlation. The
regression line slopes for the best fit lines between the 10Be production and
the 10Be measurements used in the cross correlation analysis are all in the
range 0.4-0.6. This is a particular problem for historical projections of solar
activity based on ice core measurements which assume a 1:1 correspondence. We
have made other tests of the correspondence between the 10Be predictions and
the ice core measurements which lead to the same conclusion, namely that other
influences on the ice core measurements, as large as or larger than the
production changes themselves, are occurring. These influences could be
climatic or instrumentally based. We suggest new ice core measurements that
might help in defining more clearly what these influences are and-if
possible-to correct for them.
