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I I .1 I I I I I I I I I I I I I I I I focused on case studies from the Experimental Period. All the data reduction for these case studies was conducted without knowledge of the randomized decision on which days were active seeding versus simulated seeding (sand flares). The first step in the data analysis was to compute plumes estimated to be the area of effect for a given seeding period. These areas were computed based on winds in the cloud region, radar echo movement, and an estimate of dispersion. Estimated areas of effect were given to the University of Delaware group, shortly after the end of the field season, for use in the raingage analysis. The next step in the analysis was to obtain measurements of cloud liquid water content and updraft speeds from the airborne data tapes and voice tapes. These data were plotted on the PPI ec:ho over- lays at their corresponding positions and times. Sequential PPI's were used to construct echo time-histories for each seeding period. On 8 of the 10 case studies RHI data was available. Sequen- tial RHI's, from the core region of selected cells, were used to construct time-height cross sections of the radar reflectivity values. These time-height diagrams were then utilized in the interprl~tation of precipitation growth mechanisms, cloud tops, and precipitation fallout patterns. Of the 10 cases studied, 4 cases were control or simUllated seed events. All four of these cases showed some potential for dynamic seedability. In most cases showers were forming vi.a a warm rain process. Cloud bases were near 5,000 ft (+150 to +180C), first echoes formed near 15,000 ft (_20C) and cloud tops werH generally in the 17, 000 to 20, 000 ft range (- 5 to -10 OC). In a. few cases there was evidence of a slow, weak ice phase precipitation mechanism occurring. 122 _. '.