1982 Volume 60 Issue 6 Pages 1215-1226
One of the subprograms of the Polar-Experiment North (POLEX-North), "Observation of. Wintertime Clouds and Precipitation" was carried out at Inuvik (68°22'N, 133°42'W), Northwest Territories, Arctic Canada, from December 1, 1979 to January 5, 1980. When the warm air from the Pacific Ocean advected over the observation station, dendritic crystals were observed as rimed and snowflakes, and at times, graupel particles. Corresponding to these snow crystals, a PPI radar echo showed convective type. On the other hand, when the polar air masses covered over the observation station, as expected from the temperature condition, the prevailing shapes . of snow crystals were combination of bullets, columns and crossed plates. Corresponding to these air masses, a PPI radar echo was a stratiform type. The maximum precipitation intensities in a successive snowfall during the observation period were in the order of 10-3 to 100mm•hr-1. Calculating the mass using the number flux and the maximum precipitation intensity, they fell into the range between 1×10-3mg and 1×10-2mg. The equivalent diameters corresponding to these masses were from 0.12mm to 0.27mm. The Z-R relation, Z=13R1.2 and Z=9R1.1 were obtained for crossed plates and column type snow crystals, respectively. These relations were nearly equal to Z=10R1.0 for ice crystals introduced by Sato et al. (1981) for the light precipitation intensity during the summer season at the South Pole. About the relation between the maximum size and number flux, the increase in number flux increased the maximum size when the cloud thick-ness was thick and the increase in number flux decreased the maximum size when the cloud thickness was very thin. Based on the relation above described, a correlation between cloud thickness, maximum and minimum temperatures in clouds, weather conditions of synoptic scale and the shapes of snow crystals was summarized in Fig. 15.
