Intercomparison of sampling and measurement of 7Be in air at four high-altitude locations in Europe

For several years 7Be measurements have been conducted at high-altitude stations in Austria (Sonnblick, 3106 m), Switzerland (Jungfraujoch, 3580 m), Germany (Zugspitze, 2962 m), and Italy (Mt. Cimone, 2165 m) with the aim to support a study on vertical ozone transport in the Alps (VOTALP project). Aerosol samples, collected on filtering media with high volume samplers, are analysed for 7Be by high-resolution γ-spectrometry. Prior to evaluation of the 7Be time series of the four stations, both sampling and measurement procedures were checked for comparability. The results of an intercomparison exercise performed within the mentioned project are reported.