Aircraft borne optical in-situ size distribution measurements were performed within Arctic boundary layer clouds, with a special emphasis on the cloud top layer, during the VERtical Distribution of Ice in Arctic Clouds (VERDI) campaign. The observations were 5 carried out within a joint research activity of seven German institutes to investigate Arctic boundary layer-, mixed-phase clouds in April and May 2012. An instrumented Basler BT-67 research aircraft operated out of Inuvik over the Mackenzie River delta and the Beaufort Sea in the Northwest Territories of Canada. Besides the cloud particle and hydrometeor size spectrometers the aircraft was equipped with instrumentation for aerosol, radiation and other parameters. Inside the cloud, droplet size distributions with monomodal shapes were observed for predominantly liquid-phase Arctic stratocumulus.

- "M. Klingebiel1, A. de Lozar2, S. Molleker3, R. Weigel1, A. Roth3, L. Schmidt4, J. Meyer5,6, A. Ehrlich7, R. Neuber4, M. Wendisch7, and S. Borrmann1,3"