| Title | Modeling cosmogenic radionuclides 10Be and 7Be during the Maunder Minimum using the ECHAM5-HAM general circulation model |
| Author | Heikkila, U.; Beer, J.; Feichter, J. |
| Author Affil | Heikkila, U., Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz, Dubendorf, Switzerland. Other: Max-Planck- Institut für Meteorologie, Federal Republic of Germany |
| Source | Atmospheric Chemistry and Physics, 8(10), p.2797-2809. Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1680- 7316 |
| Publication Date | 2008 |
| Notes | In English. Published in Atmospheric Chemistry and Physics Discussion: 1 November 2007, http://www.atmos-chem-phys- discuss.net/7/15341/2007/acpd-7-15341-2007.ht ml; accessed in April, 2010. 46 refs. GeoRef Acc. No: 299975. CRREL Acc. No: 64004514 |
| Index Terms | aerosols; precipitation (meteorology); boundary layer; carbon isotopes; climatic change; isotopes; metals; radioactive isotopes; sedimentation; solar activity; stratosphere; Antarctica--Dome C; Greenland-- Milcent; Antarctica--South Pole; alkaline earth metals; Antarctica; Arctic region; atmospheric precipitation; atmospheric transport; Be-10; Be-7; beryllium; C-14; carbon; Cenozoic; climate change; climate forcing; Dome C; ECHAM5-HAM; general circulation models; Greenland; Holocene; ice cores; Maunder minimum; Milcent Greenland; Quaternary; seasonal variations; South Pole; sulfates; transport; tree rings; Wilkes Land |
| Abstract | All existing 10Be records from Greenland and Antarctica show increasing concentrations during the Maunder Minimum period (MM), 1645-1715, when solar activity was very low and the climate was colder (little ice age). In detail, however, the 10Be records deviate from each other. We investigate to what extent climatic changes influence the 10Be measured in ice by modeling this period using the ECHAM5-HAM general circulation model. Production calculations show that during the MM the mean global 10Be production was higher by 32% than at present due to lower solar activity. Our modeling shows that the zonally averaged modeled 10Be deposition flux deviates by only ~8% from the average increase of 32%, indicating that climatic effects are much smaller than the production change. Due to increased stratospheric production, the 10Be content in the downward fluxes is larger during MM, leading to larger 10Be deposition fluxes in the subtropics, where stratosphere- troposphere exchange (STE) is strongest. In polar regions the effect is small. In Greenland the deposition change depends on latitude and altitude. In Antarctica the change is larger in the east than in the west. We use the 10Be/7Be ratio to study changes in STE. We find larger change between 20° N-40° N during spring, pointing to a stronger STE in the Northern Hemisphere during MM. In the Southern Hemisphere the change is small. These findings indicate that climate changes do influence the 10Be deposition fluxes, but not enough to significantly disturb the production signal. Climate-induced changes remain small, especially in polar regions. |
| URL | http://www.atmos-chem-phys.net/8/2797/2008/acp-8-2797-2008.pdf |
| Publication Type | journal article |
| Record ID | 88371 |