Production rate and climate influences on the variability of ¹⁰Be deposition simulated by ECHAM5‐HAM: Globally, in Greenland, and in Antarctica

Abstract

Ice core concentrations of 10Be are used as a proxy for solar activity, but they might be affected by atmospheric transport and deposition and their changes. During the Holocene, the influence is likely to be small, but during glacials it has to be accounted for. First, the climate influence has to be understood during the present climate. This study uses an ECHAM5‐HAM 30‐year climatological simulation of 10Be to investigate the production and climate‐related influences on 10Be deposition with focus on Greenland and Antarctica. We examine the climate modes driving snow accumulation and hence potentially 10Be deposition over a climatologically relevant period. The North Atlantic Oscillation (NAO) is found to be the main driver of changes in precipitation and 10Be deposition in Greenland, in agreement with previous studies. In Antarctica, the picture is more complex as precipitation and 10Be deposition are only weakly correlated with the Southern Annular Mode (SAM), El Niño‐Southern Oscillation (ENSO), or Zonal Wave 3 pattern (ZW3). The results suggest that on seasonal scale, 10Be deposition is linked with both precipitation rate and tropopause height, mainly due to the similar seasonal cycle. However, the correlation with tropopause height persists on the annual time scale. All in all, 10Be variability in Antarctica is an interplay of several processes whose contribution varies in time and space. When interpreting 10Be ice core records for solar activity, the time scale is essentially important. On seasonal scale, the 10Be signal is dominated by weather influences, but on multiannual scales, the production rate is the main driver. On multidecadal scale, large long‐term trends in climatic factors have the potential to distort the signal again as is seen in 10Be records during glacials. This study shows how climate modes connect to 10Be variability and how this connection could be used to correct for the climate impact. The established connections during present climatic conditions can be used as a basis to investigate these connections during glacial climate in a glacial model simulation.

Beryllium-10 concentrations in the hyper-arid soils in the Atacama Desert, Chile: Implications for arid soil formation rates and El Niño driven changes in Pliocene precipitation

“…For example, the ECHAM5-HAM model predicted that the precipitation at the sampling site is greater than 2 mm per day (Heikkilä and Smith, 2013), when in fact the long term average precipitation at our site is less than 2 mm per year (Hartley and Chong, 2002;Rech et al, 2006). The same model predicted a modern 10 Be dry deposition rate $6 Â 10 4 atoms cm À2 yr À1 in the Atacama (Heikkilä and Smith, 2013), in near agreement with our measured flux of 3.7 ± 0.6 Â 10 4 atoms cm À2 yr À1 . The F 10Be at our field site is also comparable to the low 10 Be flux of $1 Â 10 4 atoms cm À2 yr À1 observed in the Dry Valley of Antarctica, which has a similar hyper-arid climate (Bettoli et al, 1993).…”

Synchronizing the Greenland ice core and radiocarbon timescales over the Holocene – Bayesian wiggle-matching of cosmogenic radionuclide records

“…We focus our analysis on the period where dendrochronologically dated high-quality 14 C measurements on tree rings are available. While this is theoretically the case back to 12 560 cal BP (calibrated before present, AD 1950, Friedrich et al, 2004, the accuracy of the oldest part of treering chronology has recently been questioned (Hogg et al, 2013) causing a gap in the 14 C records underlying IntCal13 around 12 000 cal BP (Reimer et al, 2013). Hence, we limit our analysis to the Holocene where dendrochronological and 14 C-data replication is high and most robust (Reimer et al, 2013;Friedrich et al, 2004).…”

<sup>10</sup>Be in late deglacial climate simulated by ECHAM5-HAM – Part 1: Climatological influences on <sup>10</sup>Be deposition

“…There is a secondary maximum in the tropics due to the maximum precipitation rate; however, the 10 Be air concentrations are low due to the convective uplifting of air from the surface, where 10 Be production is minimal. The temporal variability of 10 Be deposition has been studied in detail by Heikkilä and Smith (2013a). They show that 10 Be deposition strongly correlates with precipitation rate on short time scales (monthly).…”