The Feasibility of Operational Cloud Seeding in the North Platte River Basin Headwaters to increase Mountain Snowfall

Home Browse Search

F) and an improved estimate of precipitation increase expected from operational seeding. Other work tasks of the design phase will entail contracting. Contracting work may include site surveying, modeling, equipment acquisition, equipment installation /removal and maintenance, some t environmental compliance studies, and field study data and seeding result evaluation. Contracts will vary in work details but all must clearly spell out work items, supervision, work site requirements, and equipment provision. Reclamation must provide guidance to program components and participation in study analyses when appropriate. 3.3. Cloud Modeling Studies Numerical modeling of winter orographic clouds has significantly improved in the past 20 years and faster computers have facilitated improvements. These conditions have led to increases in the ' understanding of cloud airflow and microphysical processes (Young, 1974; Cotton et al., 1986; Bruintjes et al., 1992). High resolution three - dimensional modeling can now assist the study of winter cloud precipitation processes for areas such as the Headwaters Region. A few results of the RAMS model's simulation of several storm days of the 1998 and 1999 winters in the Headwaters Region are given in section 4.6.1. Modeling with a sophisticated model such as RAMS is needed to assist the design process for the Headwaters Region. Model runs should include simulation of effects of cloud seeding for comparison with nonseeded model results and field measurements. Comparisons of modeling results with field measurements are needed to study model deficiencies and possibly improve the model. Routine application of a model during the operational seeding phase will assist with weather and cloud forecasting, operations planning, and the provision of covariate information for the evaluation process. Modeling can help assess when atmospheric conditions are suitable for cloud seeding in the Headwaters Region. This information will assist design phase studies and possibly provide valuable information for locations where equipment is not installed. The availability of affordable, powerful computer workstations will allow use of sophisticated models for ' cloud seeding targeting decisions. Processes of particular interest that will be tested in a model include the three - dimensional airflow and associated transport and diffusion of ground - released seeding agents, and the growth and fallout of precipitation particles. The model should be tested for determining likely seeding release points for individual storms. Different cloud treatment strategies should be tested through modeling and as possible in seeding trials. 3.4. Cloud Seeding Hypotheses A conceptual operational seeding model specific for the Headwaters Region will emerge from the design ' phase. Specific component hypotheses that are appropriate for the conceptual seeding model will be generated. The design phase will seek answers for each hypothesis. The following presents loosely stated examples of hypotheses that may apply to the Headwaters Region. Properly constructed hypotheses will be developed upon completion of design studies. The seeding hypotheses given here are based on knowledge gained in the COSE experiments ( Rauber et al., 1986; Rauber and Grant, 1986; Rauber, 1987), the Bridger Range Experiment (Super, 1974; Super and Heimbach, 1983), the more recent Grand Mesa experiments (Super et al., 1986; Holroyd et al., 1988; Super and Boe, 1988), and recent Wasatch Plateau, Utah experiments (Super, 1999; Super and Holroyd, 1994; Super, 1995; Super; 1996; Super and Holroyd, 1997; Holroyd and Super, 1998; Holroyd et al., 1995). , The seeding hypotheses are based on dealing with orographically- enhanced supercooled winter clouds over the Park Range, using ground -based high - elevation propane dispensers and /or AgI generators. 10