To characterize the microphysical properties of Arctic low‐level clouds and their year‐round variations, in situ measurements of cloud particles began at the Mount Zeppelin Observatory (78°56′N, 11°53′E, 474 m above mean sea level (asl)) in Ny‐Ålesund, Spitsbergen, in October 2013. In June 2014, size distribution measurements of the precipitating particles using an optical disdrometer also began. In this paper, we report the seasonal variations in the microphysical properties of clouds and their relationships to aerosols by focusing on the ACI index values in summer (clean air) and winter–spring (Arctic haze) as the definitive metric.

- M. Koike , J. Ukita, J. Ström, P. Tunved,M. Shiobara, V. Vitale, A. Lupi, D. Baumgardner, C. Ritter, O. Hermansen, K. Yamada , and C. A. Pedersen