WARM FOG MODIFICATION

A program was initiated to investigate the treatment of warm fogs by hygroscopic materials. The philosophy of the program has been to conduct interactive field experiments and modeling studies aimed ultimately at the development of a computational technique which could explore hygroscopic treatment effects with a variety of material, environment, and source parameters. Field programs were carried out at Santa Rosa and Columbia, California, using three, side-by-side, C-47 aircraft to dispense sized materials. A sampling aircraft then flew across the three wakes to record the treatment effects through observations of backscatter, liquid water content, and droplet concentrations. A model of hygroscopic treatment was evolved which simulated aircraft release of the material into a wake region of 40 x 35 m. Growth by condensation, evaporation, sedimentation of particles and diffusion of material, natural cloud drops, and vapor were all included in the model. The model was used to explore several possible treatments, but a field validation of the model is required before carrying out extensive calculations. A brief, field program was carried out during the spring of 1969 at Lakeport, California, using only one C-47 as the treatment aircraft. The primary purpose of the program was to explore the use of larger quantities of material. Best effects were obtained with two to three successive releases in the same area. (Author)