Laserfiche WebLink
<br />A gravity wave mechanism sometimes aided the vertical AgI transport even in the presence of inversions. <br />The positioning of the gravity waves relative to the terrain and AgI generator locations was critical in <br />determining whether vertical AgI transport occurred. Since gravity wave positioning varies with time, and <br />AgI generators are at fixed locations, it can be argued that generators should be located at various <br />distances west of the Plateau across the broad upwind valley. This latter approach was modeled by <br />Heimbach and Hall (1994). <br /> <br />During more unstable conditions, the valley-released AgI was consistently transported over the Plateau. <br />The AgI plumes were consistently shallow over the Plateau top, often below lowest aircraft sampling <br />levels just 600 m above average Plateau top elevations. Prevailing cloud temperatures within the shallow <br />plumes were frequently too warm for effective ice nucleation by the AgI. <br /> <br />It has been demonstrated by model-simulations and observations that valley-released AgI is transported <br />over the Plateau during only a minority of hours with storm conditions. When transport does occur, the <br />AgI plumes are often too warm for much ice nucleation. These two factors are in agreement with previous <br />documentation from the Tushar Mountains of southern Utah (e.g., Sassen and Zhao 1993). These findings <br />suggest that valley AgI releases should be augmented' or replaced with other treatment technologies (e.g., <br />high-altitude AgI releases and propane seeding) in order to increase the efficiency of the Utah operational <br />cloud seeding program. <br /> <br />~. <br /> <br />23 <br /> <br />k.. <br />