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

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Heikkilä, U, Smith, AM
• Format: Article in Journal/Newspaper
• Language: English
• Published: AMERICAN GEOPHYSICAL UNION 2013
• Subjects: radionuclides; CLIMATES; EARTH ATMOSPHERE; OSCILLATIONS; DEPOSITION; SOLAR ACTIVITY; Greenland; Antarc*; Antarctica; Antarctica Journal; ice core; North Atlantic; North Atlantic oscillation
• Online Access: http://apo.ansto.gov.au/dspace/handle/10238/4676; https://doi.org/10.1002/jgrd.50217

Ice core concentrations of Be-10 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 Be-10 to investigate the production and climate-related influences on Be-10 deposition with focus on Greenland and Antarctica. We examine the climate modes driving snow accumulation and hence potentially Be-10 deposition over a climatologically relevant period. The North Atlantic Oscillation (NAO) is found to be the main driver of changes in precipitation and Be-10 deposition in Greenland, in agreement with previous studies. In Antarctica, the picture is more complex as precipitation and Be-10 deposition are only weakly correlated with the Southern Annular Mode (SAM), El Nino-Southern Oscillation (ENSO), or Zonal Wave 3 pattern (ZW3). The results suggest that on seasonal scale, Be-10 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, Be-10 variability in Antarctica is an interplay of several processes whose contribution varies in time and space. When interpreting Be-10 ice core records for solar activity, the time scale is essentially important. On seasonal scale, the Be-10 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 Be-10 records during glacials. This study shows how climate modes connect to Be-10 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. © 2013, American Geophysical Union.