Polar ice cores provide a wealth of information on past climate through a well stratified archive of past snow, firn and ice as well as entrapped atmosphere. Size, shape and number of air bubbles and the air content in ice cores are believed to preserve the pore-space structure at the time of firn-ice transition and therefore provide information on temperature or accumulation (Spencer et al., 2006) or even local insolation (Raynaud et al., 2007). In case of the air content, it may be influenced by temperature, accumulation and pressure (ice sheet elevation) on a longer time-scale or on shorter time-scale by imprinted structural modifications with changing surface snow properties or changing firnification being potential candidates.For low accumulation sites like Vostok and EDC, changes in air content linked to stratigraphic heterogeneity has been found to be non existent or comparable with the uncertainty of the measurement. On high accumulation sites seasonal variations in air content of up to 25 % have been found and interpreted as sealing effect of summer snow layers by winter snow layers (Martinerie, 1992).For the case of DML we revealed a possible link between the air content and the stratigraphic heterogeneity of ice on the B 34 ice core close to EDML from the depth interval 193.0 to 194.0 m by combining total air measurements with high-resolution line-scans of ice sections.
Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 1: The Changing Arctic and Antarctic > WP 1.1: Role of Ice Sheets in the Earth System