Discrimination of micrometre-sized ice and super-cooled droplets in mixed-phase cloud

Preliminary experimental results are presented from an aircraft-mounted probe designed to provide in situ data on cloud particle shape, size, and number concentration. In particular, the probe has been designed to facilitate discrimination between super-cooled water droplets and ice crystals of 1-25 mum size within mixed-phase clouds and to provide information on cloud interstitial aerosols. The probe acquires spatial light scattering data from individual particles at throughput rates of several thousand particles per second. These data are logged at 100ms intervals to allow the distribution and number concentration of each particle type to be determined with 10m spatial resolution at a typical airspeed of 100ms(-1). Preliminary results from flight data recorded in altocumulus castellanus, showing liquid water phase, mixed phase, and ice phase are presented to illustrate the probe's particle discrimination capabilities. (C) 2000 Elsevier Science Ltd. All rights reserved.