Microphysical characteristics of frozen droplet aggregates from deep convective clouds

During the 2012 Deep Convective Clouds and Chemistry (DC3) experiment the National Science Foundation/National Center for Atmospheric Research Gulfstream V (GV) aircraft sampled the upper anvils of two storms that developed in eastern Colorado on 6 June 2012. A cloud particle imager (CPI) mounted on the GV aircraft recorded images of ice crystals at altitudes of 12.0 to 12.4 km and temperatures (T) from -61 to -55 degrees C. A total of 22 393 CPI crystal images were analyzed, all with maximum dimension (D-max) < 433 mu m and with an average D-max of 80.7 +/- 45.4 mu m. The occurrence of well-defined pristine crystals (e.g., columns and plates) was less than 0.04% by number. Single frozen droplets and frozen droplet aggregates (FDAs) were the dominant habits with fractions of 73.0% (by number) and 46.3 % (by projected area), respectively. The relative frequency of occurrence of single frozen droplets and FDAs depended on temperature and position within the anvil cloud.