High-resolution records of the beryllium-10 solar activity proxy in ice from Law Dome, East Antarctica: measurement, reproducibility and principal trends

Three near-monthly resolution Be-10 records are presented from the Dome Summit South (DSS) ice core site, Law Dome, East Antarctica. The chemical preparation and Accelerator Mass Spectrometer (AMS) measurement of these records is described. The reproducibility of Be-10 records at DSS is assessed through intercomparison of the ice core data with data from two previously published and contemporaneous snow pits. We find generally good agreement between the five records, comparable to that observed between other trace chemical records from the site. This result allays concerns raised by a previous Antarctic study (Moraal et al., 2005) about poor reproducibility of ice core Be-10 records. A single composite series is constructed from the three ice cores providing a monthly-resolved record of Be-10 concentrations at DSS over the past decade (1999 to 2009). To our knowledge, this is the first published ice core data spanning the recent exceptional solar minimum of solar cycle 23. Be-10 concentrations are significantly correlated to the cosmic ray flux recorded by the McMurdo neutron monitor (r(xy) = 0.64, with 95% CI of 0.53 to 0.71), suggesting that solar modulation of the atmospheric production rate may explain up to similar to 40% of the variance in Be-10 concentrations at DSS. Sharp concentration peaks occur in most years during the summer-to-autumn, possibly caused by stratospheric incursions. Our results underscore the presence of both production and meteorological signals in ice core Be-10 data.