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<br />I <br /> <br />I <br /> <br />2. HAIL SUPPRESSION <br /> <br />I <br /> <br />Studies of hailstorms and hail suppression have <br />been an area of personal involvement throughout most <br />of my career. This is the work with which I am most <br />familiar, and as such, I may tend to be excessive in <br />concentrating on the results of these studies. I feel <br />somewhat justified by the fact that there is a large <br />degree of commonality in the seeding responses <br />illustrated here to those seen in precipitation <br />enhancement studies. <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />For studies of hail and hail suppression, we have <br />applied a hybrid form of the model which employs <br />discrete microphysical techniques to the treatment of <br />precipitating ice. Initial efforts in the development of <br />the scheme were performed in a one-dimensional time- <br />dependent framework as reported in Farley et al. <br /> <br />I <br /> <br />I <br /> <br />~LACEBO 17:49:25 <br /> <br /> <br />.~ <br /> <br />I <br /> <br /> <br />I <br /> <br />I <br /> <br />17:52:24 <br /> <br />~~ <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />20 <br /> <br />15 <br /> <br />10 <br /> <br />5 <br /> <br />(1976). Subsequent studies in a two-dimensional <br />framework are reported in Farley and Orville (1982, <br />1986) who applied second generation seeding <br />techniques to simulations of the Fleming supercell case. <br />As was noted earlier, the use of these simple seeding <br />techniques tended to predict coupled effects; both rain <br />and hail showed decreases due to seeding for this case. <br /> <br />Third generation seeding techniques were first <br />applied to studies of hail suppression beginning with <br />simulations of a multicellular hailstorm case from the <br />Alberta Hail Project (Farley, 1987). The model <br />simulation of the natural case produced a very good <br />replication of the observed storm, especially the feeder <br />cell, as can be seen by comparing Figs. 9 and 10. There <br />is a high degree of fidelity between the observed and <br />modeled radar reflectivity in terms of magnitudes, <br />structure and evolution. <br /> <br />. <br />. <br /> <br />PLACEBO 17:56:53 <br /> <br />~~j2 <br /> <br />. <br />. <br />4 <br />Z <br />.0 <br />. <br />. <br />4 <br />Z <br />0 <br />. ! <br />. <br />.. 5 <br />~ <br /> &II <br /> :z: <br /> <br />o <br /> <br />OlSTAHCE (ka) <br /> <br />Fig. 9. A time sequence of vertical cross sections of observed radar reflectivity showing the evolution of the <br />untreated feeder cell (placebo) for the 26 July 1983 hailstorm. Reflectivity contours are in 5 dB intervals starting <br />at 20 dBZ. with contours highlighted at 10 dB intervals. The cross sections are oriented along the direction of the <br />midlevel winds. <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />.. <br /> <br /> <br />2 <br />o <br />. <br />. <br />.. <br />2 <br /> <br />~ <br />~n.. <br /> <br /> <br />20 <br /> <br />IS <br /> <br />10 <br /> <br />S <br /> <br />23 <br />