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<br />Average ~ir temperature at or less than 0.00 C. <br /> <br />At least two Rosemount trips anywhere within the 2-hour <br />block. <br /> <br />Average wind direction greater than 180 deg true and less than <br />330 deg true. <br /> <br />Average wind speed greater than 1.0 m/s. Because of the high <br />starting threshold of the Hydrotech (about 1.3 m/s), consider <br />its speed to be 0.7 mls whenever it is not turning in the <br />calculation of mean speed. <br /> <br />Cloud seeding stops at all 3 dispensers whenever the above mean conditions are <br />no longer met for the past hour andlor the number of Rosemount trips is less <br />than 2 over the past 2 hours. Cloud seeding stops at the north and south <br />satellite dispensers whenever they have lost communication with the base unit <br />for more than 12 hours. Appendix A contains the decision flowcharts for <br />turning the dispensers on and off. Appendix B contains the algorithms for <br />both the base and satellite units. <br /> <br />The wind direction criteria to commence seeding are based on an examination of <br /> <br />a map of the target area and seeding sites, allowing for the usual veering of <br />the wind with height above terrain, and upon examination of the High Altitude <br /> <br />seeding Site (BAS) winds during radiometer-measured SLW episodes from early <br />1991. The BAS is a similar site to Freds Flat in relation to the downwind <br /> <br />higher terrain of the Wasatch Plateau. The wind speed criteria were also <br />based on BASlradiometer data examination. <br /> <br />Examination of data from a windy site in California (Shasta Bally) revealed <br /> <br />few cases with icing rates less than two per hour. However, another nearby <br /> <br />site protected from strong winds often had only one or two trips per hour <br />(David Reynolds, personal communication). Development of rime ice or even <br />"feather rime" on the Rosemount probe during periods of drifting fog could <br />cause an occasional single trip. An equation developed during earlier <br /> <br />research on the Grand Mesa of Colorado related cloud liquid water content <br /> <br />(LWC) to Rosemount trips. For the frequent light (1-3 m/s) winds measured at <br /> <br />10 <br />