The Separation of Simple and Complex Ice Particles Based on Aircraft Observations

Monday, 15 December 2014: 2:10 PM
Carl G Schmitt, National Center for Atmospheric Research, NESL-MMM, Boulder, CO, United States, Andrew Heymsfield, National Center for Atmospheric Research, Boulder, CO, United States and Paul Connolly, University of Manchester, Manchester, United Kingdom
The impact of ice clouds on weather and climate is a function of ice particle shape which directly influences their radiative scattering properties and sedimentation rates. Many weather forecast and climate models use two categories to represent ice cloud particles: cloud ice, and snow. The discrimination between cloud ice and snow is generally not observationally based. Analysis of particle imagery data from high-resolution aircraft particle imaging probes indicates that atmospheric ice particles can easily be differentiated objectively according to their “complexity”: into single crystals and complex aggregates of crystals. In this presentation, we will present results from a survey of aircraft data collected under a variety of different atmospheric conditions. Results show that the particle size where the dominant particle type switches from one type to the other is typically around 150 microns but can vary substantially based on cloud type and temperature.