Tuesday, 4 June 2002: 8:45 AM
Particle spectra in stratiform winter clouds
It is necessary to document observations describing cloud particle spectra in order: a) to increase our knowledge of precipitation growth processes, b) to better parameterize cloud and precipitation characteristics within climate and weather forecasting models, and c) to develop improved techniques to remotely sense cloud and precipitation properties. Data from 81 research flights conducted during the First and Third Canadian Freezing Drizzle Experiments, the FIRE Arctic Cloud Experiment, and the Alliance Icing Research Study have been analyzed to determine the cloud particle spectra within glaciated, mixed phase, and all liquid clouds. This represents a data set which includes approximately 32, 000 km of in-cloud measurements at temperatures mainly below freezing in stratiform winter clouds. Distributions of spectra as a function of diameter (D), D2, D3 and D6 have been determined over a size range from several microns to several millimeters using Particle Measurement System (PMS) probes. The data clearly show that the shape of the spectra are temperature dependent, and of course, dependent on the liquid fraction. There are some differences between the measurement locations (maritime, continental and Arctic). Comparisons will be made with previous work on this subject. The implications of the spectra shapes for cloud and precipitation studies will be presented.