The Cloud Indirect Forcing Experiment (CIFEX) took place in April 2004, during which time aerosols from two Asian dust storms arrived at the Northern California coast. Major goals of the experiment were to intercept advected Asian dust and aerosol plumes, and to investigate the impacts of aerosols on clouds. Flights were conducted over the Pacific using the NSF funded Wyoming King Air meteorological aircraft. Cloud probes included an FSSP, 1D-C, 2D-C, Gerber LWC probe, and the Wyoming Cloud Radar. Aerosols were sampled using a CCN, PCASP, CPC, and SMPS. Clouds were sampled in a porpoise-style flight track, incorporating long level samples with profiles that extended both above and below cloud.
The current work addresses the interactions between aerosols and low-level stratiform clouds. Stratus cloud drop concentrations were observed to vary from 25 to 150 cm-3, while sub-cloud CN concentrations were observed to vary from 25 to 300 cm-3. Results show a correlation between droplet number and accumulation-mode aerosol concentration, while indicating that liquid water content is independent of sub-cloud aerosol concentration. Further analysis has made use of the Wyoming Cloud Radar to obtain a running profile of clouds and identify regions of drizzle. Continuing work is concerned with investigating the changes in cloud microphysics and structure in the presence of drizzle, and the interactions between drizzle production and aerosol concentration.