Exploration of 10Be ice core records using a climatological model approach: Cosmogenic production versus climate variability

• Main Author: Elsässer, Christoph
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2013
• Subjects: 530; 530 Physics; ice core
• Online Access: https://archiv.ub.uni-heidelberg.de/volltextserver/16349/; https://archiv.ub.uni-heidelberg.de/volltextserver/16349/1/Dissertation_Els%C3%A4sser_2013.pdf; https://doi.org/10.11588/heidok.00016349; https://nbn-resolving.org/urn:nbn:de:bsz:16-heidok-163495

Ice core records of 10Be basically offer a wide range of applications in climate research. However, atmospheric transport and deposition processes still hamper their straightforward interpretation. This work aims at establishing a climatological, data-based model attempt which allows for the first quantitative simulation of 10Be ice concentration on a time scale of several 10kyr. To this end, a global atmospheric multi-box model is configured for the simulation of aerosol-borne radionuclides using extensive observations of natural and artificial nuclides. Validation with short-lived 7Be reveals that the model is capable to simulate its spatio-temporal distribution in the global atmosphere, thereby providing insight into the respective circulation of 10Be. To simulate 10Be ice core records, the model is coupled to a basic air-firn-transfer module based on spatial 10Be variations in polar ice. The model results, driven by precipitation/accumulation rate changes as well as solar and geomagnetic activity, closely reproduce the main features of observations on the Holocene and 75kyr timescale. Regarding the latter, climate-related accumulation rate changes dominate the ice concentration imposing variations of up to 300%. In contrast, incomplete atmospheric mixing of 10Be dampens the geomagnetic modulation of 10Be at polar sites by up to 50% compared to the global atmospheric 10Be inventory. These findings basically challenge the use of ice core 10Be as proxy for past geomagnetic activity.