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III. EAGLE RIVER VALLEY-CLIMAX STUDY The general purpose of the first study was to develop laboratory airflow models which would be adequate in estimating airflow and atmospheric transport-dispersion characteristics during winter storms (northwest winds) over the Eagle River Valley-Climax topographic complex. Both barostromatic and neutral airflow models were investigated because detail information on the meteorological characteristics associated with the winter storms were not established at the outset. The study was different from the other two research efforts in that 1) the topography is principally a long narrow valley, but compli- cated by singular and blocking ridges and 2) the availability of field data made field and model data comparisons more complete than the other two studies. The contents of this section have been condensed from reports submitted by Orgill et ~., (Refs. 30 and 31). Field Experimental Program The basic features of the Climax weather modification experiment have been discussed by Grant et al., (Ref. 18) and Chappell (Ref. 7). Only information pertinent to~his study will be summarized. 1. Network of generators Six silver-iodide ground generators are used in the project. These are Colorado State University modified sky-five, acetone, needle-type ground generators. The seeding rate of the generators may vary from 2 gm/hr to 200 gm/hr of silver-iodide, but are usually set at 15-20 gm/hr which produces about 1014 particles per gm silver-iodide effective at -120C and 4x1015 particles per gm silver-iodide effective at -200C. Two of the six generators are located in the Eagle River Valley which is oriented in 'a northwest-southeast direction from the primary target area (Chalk Mountain). Only northwest wind flow has been used for topographic modeling (Fig. 3-1). The two generators located in the Eagle River Valley were placed near the towns of Minturn and Redcliff. Both generators are deep in the valley but the location of the Minturn generator is upwind from Battle Mountain. 2. Criteria for experimental day The decision to turn on the generators during normal operations was made with a randomization scheme. The sampling period was a 24-hour interval of time. The weather criteria used for selecting the experimental days to be used for the prototype studies were: a) deep northwest (270-3600) airflow (5-15 mps) over the area, and b) overcast to broken orographic clouds with some precipitation but of light intensity. ~ = G ~ 24