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1 <br />I G5. Additional precipitation caused by cloud seeding occurs in amounts that are detectable in <br />the intended targeted areas when compared to control amounts. <br />' The seeding hypotheses resulting from the design phase are expected to be largely based on the static <br />seeding mode. However, the modeling results of Orville et al. (1987) suggested that seeding layer clouds <br />may cause embedded convection under some atmospheric conditions, leading to enhanced liquid water <br />production. Because dynamic effects may sometimes occur by presumed static seeding, observations in <br />the Headwaters Region must be viewed in light of possible dynamic effects under favorable atmospheric <br />conditions. <br />The field measurements necessary to deal with seeding hypotheses G1 -G5 include some or all of the <br />following. <br />M1. Assess SLW over the mountain barrier with radiometers and /or icing rate meters. <br />1 <br />J <br />1 <br />1 <br />M2. Measure propane gas dispenser flow rate and nozzle temperature. Measure AgI <br />generator solution flow rate and flame temperature. Automatically telemeter <br />measurements via radio to a central monitoring site. <br />M3. Measure ambient temperature, humidity and winds at seeding device locations and at <br />other selected locations of the mountain barriers. Telemeter measurements via radio to <br />the central monitoring site. <br />M4. Estimate transport and diffusion of the seeding created ice particles with mobile <br />detectors mounted on a four -wheel drive vehicle, at the Storm Peak Laboratory, and <br />possibly one other fixed location in the Medicine Bow Mountains. Measuring devices <br />may include 2D probes, ice nucleus counters, tracer gas detectors, and a cloud droplet <br />measuring device (FSSP). Other equipment may include (optional) scanning Doppler <br />radar for assessing winds to and from the radar and precipitation, and a radar profiler to <br />monitor the vertical distribution of horizontal winds and virtual temperature. <br />M5. Measure precipitation with high resolution gauges with specifications to resolve to within <br />five minutes and 0.1 millimeters of water equivalent. Gauge spacing will be determined <br />during the project design phase. <br />11 <br />G1. There exists SLW in excess of that naturally converted to snowfall when the prevailing <br />wind produces a positive component normal to the mountain barrier. <br />G2. Cloud seeding devices (propane gas or AgI) reliably lead to the creation of ice particles in <br />an environment favorable to the survival of ice, while in transport to cloud volume <br />containing SLW. <br />G3. Seeding creates ice crystals in numbers, estimated by models and limited measurements, to <br />be adequate in concentration, that turbulence and /or convection lead to transport and <br />' <br />diffusion throughout a substantial portion of the targeted SLW zone. <br />G4. Favorable environments exist and growth time is adequate during transport such that ice <br />' <br />particles can grow large enough to reach the intended target area before <br />evaporation /sublimation occurs in the lee -side airflow. <br />I G5. Additional precipitation caused by cloud seeding occurs in amounts that are detectable in <br />the intended targeted areas when compared to control amounts. <br />' The seeding hypotheses resulting from the design phase are expected to be largely based on the static <br />seeding mode. However, the modeling results of Orville et al. (1987) suggested that seeding layer clouds <br />may cause embedded convection under some atmospheric conditions, leading to enhanced liquid water <br />production. Because dynamic effects may sometimes occur by presumed static seeding, observations in <br />the Headwaters Region must be viewed in light of possible dynamic effects under favorable atmospheric <br />conditions. <br />The field measurements necessary to deal with seeding hypotheses G1 -G5 include some or all of the <br />following. <br />M1. Assess SLW over the mountain barrier with radiometers and /or icing rate meters. <br />1 <br />J <br />1 <br />1 <br />M2. Measure propane gas dispenser flow rate and nozzle temperature. Measure AgI <br />generator solution flow rate and flame temperature. Automatically telemeter <br />measurements via radio to a central monitoring site. <br />M3. Measure ambient temperature, humidity and winds at seeding device locations and at <br />other selected locations of the mountain barriers. Telemeter measurements via radio to <br />the central monitoring site. <br />M4. Estimate transport and diffusion of the seeding created ice particles with mobile <br />detectors mounted on a four -wheel drive vehicle, at the Storm Peak Laboratory, and <br />possibly one other fixed location in the Medicine Bow Mountains. Measuring devices <br />may include 2D probes, ice nucleus counters, tracer gas detectors, and a cloud droplet <br />measuring device (FSSP). Other equipment may include (optional) scanning Doppler <br />radar for assessing winds to and from the radar and precipitation, and a radar profiler to <br />monitor the vertical distribution of horizontal winds and virtual temperature. <br />M5. Measure precipitation with high resolution gauges with specifications to resolve to within <br />five minutes and 0.1 millimeters of water equivalent. Gauge spacing will be determined <br />during the project design phase. <br />11 <br />