Laserfiche WebLink
<br />with temperature inversions, were found to hamper vertical transport from the valleys, and up- <br />or down-valley winds at times caused poor directional targeting of seeding material. Griffith <br />et al. (1992), however, found that in unstable conditions seeding material could be transported <br />to supercooled regions of clouds over mountainous targets from a generator positioned near the <br />mouth of a canyon somewhat above the valley floor. Current evaluation of the complete set of <br />1991 Utah/NOAA experiments on seeding material transport and dispersion (by other <br />Utah/NOAA investigators) should provide a better understanding of what environments are <br />suitable for successful ground-based targeting. Future work will be aimed at quantitatively <br />assessing (directly detecting) the effects of cloud seeding from a ground-based network of <br />seeding generators. However, prior to this final assessment the techniques of ground-based <br />seeding may undergo significant changes based on the findings of current work. <br />The primary objective of the 1991 Utah/NOAA field research program was to evaluate <br />the effectiveness of ground-based generators (positioned as in the Utah operational program) in <br />delivering silver iodide to regions of orographic clouds containing supercooled liquid water. <br />Secondarily, the field program was designed to continue studies of the evolution of SLW over <br />mountainous terrain during winter storms. The research program was conducted in the vicinity <br />of the Wasatch Plateau in central Utah, after being conducted for several seasons in the Tushar <br />Mountains of southwestern Utah. The 1991 SLW studies were being done in part to confirm <br />results regarding SLW that had previously been documented for the Tushars. <br />This Final Report describes work performed by the Desert Research Institute (DR!) in <br />support of the 1991 Utah/NOAA field research program. The primary task undertaken by the <br />DR! was the description of the spatial and temporal distributions of SLW over the Wasatch <br />Plateau, and evaluation of the factors controlling SLW evolution. The microwave radiometer <br />was the primary tool used in these studies, and during the 1991 project two radiometers were <br />available; one to constantly monitor SLW at the top of the Plateau, and the other to measure <br />SL W in a new mobile-mode of operation and provide much more detail on the spatial <br />characteristics of SLW than stationary radiometers have been capable of providing. The <br />development of storms encountered during the 1991 program was given considerable attention, <br />and SLW characteristics are described in terms of their synoptic influence. Project soundings <br />were evaluated to estimate the vertical location, temperature structure, and winds in the cloud <br />layers containing SLW. K.-band radar and GOES satellite data provided additional information <br />on cloud top heights and temperatures, and the occurrence of mesoscale cloud features. Surface <br />meteorological data and rawinsonde winds were used to estimate the flux of SL W across the <br />Wasatch Plateau, and provide comparative data for similar estimates over the Tushar Mountains <br /> <br />1-2 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />