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<br />meaning except with regard to the locations of the SL W cloud measurements and seeding material source. <br />F or the Merchant Valley measurements, for example, although no SL W clouds were detected during <br />easterly flow (amounting to negative cross-barrier velocities), observations conducted from the eastern <br />Tushar Mountains would likely have encountered SL W under such conditions. <br /> <br />Finally, whereas our earlier SL W cloud discriminations were based on a manual inspection of a sequence <br />of polarization lidar returns, we have now developed computer-based criteria for the autonomous <br />identification of water-dominated cloud layers on a shot-by-shot basis. Although it is true that at this early <br />stage we manually filtered the algorithm-determined dataset to collaborate the results and identify mixed- <br />phase clouds and very low-level (less than 200 m above surface) SL W layers (both conditions still defying <br />autonomous identification due to oriented plate crystal and lidar beamwidth crossover effects), our visual <br />shot inspection produced an "error" of only a few percent of the total shots. This finding is quite <br />encouraging in that it provides the foundation for the automated analysis of lidar returns under multiphase <br />cloud conditions, the worst-case scenario for lidar studies. Such methods are of fundamental importance <br />to various climate research programs designed to characterize the cloudy atmosphere using lidar and other <br />remote sensor measurements. <br /> <br />8.7. Super, A. B., 1993: Precipitation gauge testing on the Wasatch Plateau, Utah during early 1993. <br />Bureau of Reclamation Research Report R-93-17, Denver, CO, 10 pp. <br /> <br />~" <br /> <br />INTRODUCTION <br /> <br />Field Observations were made to test an ETI (Electronic Techniques, Inc.) precipitation gauge at the High <br />Altitude Site on the western slope ofthe Wasatch Plateau in Central Utah, east of Fairview. The ETI <br />gauge should require little servicing because it is designed to automatically discharge its precipitation and <br />antifreeze mix when gauge capacity is reached. The gauge then automatically recharges itself with <br />antifreeze. It provides digitized data at a resolution of 0.0 1 in., which can be transmitted from remote <br />locations. The ETI gauge could provide a desirablealtemative to conventional recording gauges in <br />several applications, including evaluation of cloud seeding projects, if it performs as advertised. The <br />testing program was intended to determine its performance in a winter mountain environment. <br /> <br />~... <br /> <br />The tests were conducted in a small clearing within a conifer forest at latitude 390,37', longitude 1110, <br />22' elevation 8200 ft. The site is rated "over-protected" because of the close proximity of treeiof an <br />estimated height near 70 ft. all around the clearing. However, the site was convenient to serv e while <br />testing other instrumentation in a nearby open area, and was satisfactory for comparison of pr ipitation <br />gauges and snowboards. <br /> <br />The test period ran from 1400 (all times m.s.t.) on February 16, 1993, until 1000 on March 28, 1993. Data <br />collected earlier have not been analyzed because the Alter windshield on the Belfort weighing gauge was <br />several inches too high until the stated start time. That height may have been important in the very <br />,protected clearing, but adequate data exist after the shield top was adjusted to be near level with the gauge <br />orifice top. <br /> <br />CONCLUSIONS <br /> <br />The ETI precipitation gauge proved to be reliable and provided good quality data. The only problem was <br />an occasional tendency for the gauge to falsely indicated minor snowfall amounts, usually 0.01 in. snow. <br /> <br />46 <br />