RADIALLY CLASSIFIED AEROSOL DETECTOR FOR AIRCRAFT-BASED SUBMICRON AEROSOL MEASUREMENTS

A radially classified aerosol detector (RCAD) for fast characterizatio n of fine particle size distributions aboard aircraft has been designe d and implemented. The measurement system includes a radial differenti al mobility analyzer and a high-flow, high-efficiency condensation nuc lei counter based on modifications to a commercial model (TSI, model 3 010). Variations in pressure encountered during changes in altitude in flight are compensated by feedback control of volumetric flow rates w ith a damped proportional control algorithm. Sampling resolution is op timized with the use of an automated dual-bag sampling system. This ne w system has been tested aboard the University of Washington C13 la re search aircraft to demonstrate its in-flight performance capabilities. The system was used to make measurements of aerosol, providing observ ations of the spatial variability within the cloud-topped boundary lay er off the coast of Monterey, California.