Volcanic frequency during the last glacial period derived from high-resolution sulphate measurements on the Greenalnd North GRIP ice core

During the 2000 field season at North GRIP (Greenland), high-resolutionchemical analyses have been done using the Bern Continuous FlowAnalysis (CFA) system. Among other substances, sulphate (SO4=) hasbeen recorded continuously over the last glacial period, i.e. fromapproximately 100 kyr to 9.5 kyr before present. The one-centimetreresolution of the record allows us to obtain a comprehensive list ofpotential volcanic sulphuric acid events from which a frequencydistribution can be derived. Taking background sulphate into account,the events can be assigned to different strength categories. Therecord from North GRIP is then compared to other time series ofvolcanic activity, which allows us to distinguish regional, hemisphericor global events.