Evidence for climate modulation of the 10Be solar activity proxy

Abstract

We used a snow pit record in conjunction with detailed snow accumulation data and oxygen isotope records to examine atmospheric transport and deposition effects on 10Be at Law Dome, Antarctica. Data from an adjacent automatic weather station was used to date the record at snowfall event-scale resolution. In contrast to prior ice core studies in Antarctica, the snow pit record is of a sufficiently short duration (∼1 year) that 10Be fluctuations reflect mainly atmospheric transport processes rather than solar modulation of production. Elevated concentrations of 10Be were found in the late austral summer and early autumn snow, synchronous with the seasonal increase in stratospheric aerosols at Antarctic stations. A significant (P < 0.01) anticorrelation of 10Be with δ 18O occurs at the snowfall event scale. Fractionation of water isotopes at Law Dome is controlled by local and regional processes, specifically transport and local temperature. The anticorrelation seen here implies that 10Be concentration was reduced in snow from warmer air masses (characterized by less negative δ18O). There is potential for confounding solar modulation with climatic modulation if at sites such as this one, warmer meteorological influences may be associated with reduced 10Be concentrations. Quantification of the significance of this effect for the longer-term 10Be record will require analysis of longer 10Be records from different sites. Copyright 2006 by the American Geophysical Union.