Volcanic and solar particle events in the past: Atmospheric Effects and cOsmogenic Nuclides in ice cores – AEON

Volcanic eruptions and extreme solar proton events (SPEs) contribute significantly to variability in the chemical composition and dynamics of the stratosphere, which in turn can affect vertical coupling between the stratosphere and troposphere. Our knowledge of past solar and volcanic events is based on the interpretation of ice core records of the cosmogenic nuclides beryllium-10 (10Be) and chlorine-36 (36Cl), and sulfate, respectively. The 10Be signal is a proxy for past solar activity but it is also affected by stratospheric volcanic eruptions. The 36Cl/10Be ratio is used for reconstructions of SPE energy spectra, however out of these solar events, the ratio differs significantly from theoretical atmospheric production models. This deviation from the theoretical production value might be explained by different modes of transport, deposition, and post-deposition effects of 10Be and 36Cl. The 36Cl/10Be ratio must therefore be studied/modeled individually for each volcanic or solar event and for a given site.
The AEON project is based on a data-model approach, using high-precision measurements of cosmogenic nuclides and the aerosol-chemistry-climate model SOCOLv4. The objectives are 1) to obtain new 10Be and 36Cl data from the Talos Dome ice core (Antarctica) around known SPEs and to search for new SPEs between 0 and 1000CE 2) to improve the understanding of the 36Cl/10Be ratio for the determination of the SPE energy spectrum and thus improve reconstructions of past solar activity 3) to clarify the role of volcanic aerosols in the transport and deposition of 10Be 4) to characterize the effects of past volcanic eruptions and SPEs on the stratosphere, on stratosphere/troposphere exchanges and on tropospheric dynamics.