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

Abstract

Abstract. Three near-monthly resolution 10 Be 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 10 Be 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 10 Be records. A single composite series is constructed from the three ice cores providing a monthly-resolved record of 10 Be 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. 10 Be 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 ∼40 % of the variance in 10 Be 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 10 Be data.

Influence of model resolution on the atmospheric transport of <sup>10</sup>Be

“…The runs with a higher vertical resolution produce a residence time closer to the observed estimate of 1 yr (e.g. Pedro et al, 2011). There seems to be a clear link between the horizontal resolution and the tropospheric residence time of 10 Be (T63: 18 d, T42: 20 d, T21: 24 d).…”

“…The typical lag found between 10 Be deposition and cosmic ray production is in the order of 1 yr (e.g. Pedro et al, 2011). This is somewhat shorter than the typical age of air in polar stratosphere of 3-5 yr (e.g.…”

“…1 yr e.g. Pedro et al, 2011) require the use of a global model or at least one including one hemisphere. Comparison with observations has shown that they are much more sensitive to uncertainties in scavenging and atmospheric transport than short-lived tracers emitted from Earth's surface (Brost et al, 1996;Koch et al, 2006;Liu et al, 2001).…”

Volcanic and solar activity, and atmospheric circulation influences on cosmogenic 10Be fallout at Vostok and Concordia (Antarctica) over the last 60years

“…In Antarctica, the 11-yr solar cycle has been detected at Taylor Dome (Steig et al, 1996), but it is more difficult to identify at other sites, such as Dronning Maud Land, because of a low accumulation rate (Aldahan et al, 1998). At Law Dome (Antarctica), the solar modulation explains $40% of the variance in 10 Be concentrations (Pedro et al, 2011), however this relationship is based on a record covering the last 10 yr and it needs to be tested for several 11-yr solar cycles. The meteorological noise also contributes to the 10 Be signal at Law Dome for example (Pedro et al, 2006).…”

<sup>10</sup>Be in late deglacial climate simulated by ECHAM5-HAM – Part 2: Isolating the solar signal from <sup>10</sup>Be deposition

“…Hence, principal component analysis might not be able to reveal the solar signal during periods when observations disagree. Therefore we apply an alternative method, the EEMD, to analyse time series separately at two particular locations: the GRIP site in central Pedro et al, 2011;Yiou et al, 1997). We first present the modelled time series of 10 Be deposition at both sites (Fig.…”