Summary
Changes in solar activity modulate the galactic cosmic ray flux, and in turn, the production rate of cosmogenic 10Be in the Earth’s atmosphere. The best archives of past changes in 10Be production rate are polar ice cores. Key challenges in interpreting these archives as proxies for past solar activity lie in: a) separating the useful solar activity (or production) signal from the interfering meteorological (or climate) signal, and b) determining the atmospheric source regions of 10Be deposited to the ice core site. We use a monthly resolution 10Be record, spanning 2000 to 2006, and a general circulation model (ECHAM5-HAM), to investigate production and climate signals in 10Be concentrations at the Law Dome ice core site, East Antarctica. On sub-annual timescales 10Be was dominated by a concentration maximum in summer to autumn. Model results suggest that this cycle is forced by variability in the stratospheric flux of 10Be to the site. On annual timescales the correlation of 10Be with solar activity improves. We find an average atmospheric residence time for 10Be of 4-11 months, much less than the generally assumed settling out time of 2 years.