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o Evolution of hydrometeors: wind fields and growth trajectories. o Storm structure and the near-storm environment: cells, cell interactions, and prediction. The CCOPE field site is expected to have eight radars (S-band, X-band, C- band, and K-band, and both Doppler and non-Doppler) and a surface mesometeorological network totaling about 130 stations over the 200,000 km~ experimental area. As many as five upper-air observing stations will provide data for mesoscale analyses. Visible and infrared satellite data will be available in several forms. Up to 17 instrumented aircratt, including four jets and one sailplane, will be used during the 1981 field program. CCOPE will attempt to study the entire lifetimes of convective clouds, from the causal events in the planetary boundary layer to the final fallout of precipitation and dissipation of the clouds. Three storm stages are designated: prestorm, early storm, and mature storm. Although there is no distinct separation among the three stages, this classification is necessary for the sake of practical field organization. Prestorm investigations include studies of storm initiation and storm environment. The hypotheses for storm initiation include such factors as topographic triggers, atmospheric waves, effects from mature storms, large- scale features, random turbulence, and combinations of these factors. Early storm investigations have four principal objectives. They are (1) to elucidate the relative importance of different entrainment mechanisms in growing High Plains cumulus clouds; (20) to determine the primary ice formation regions in the High Plains cumulus clouds, particularly the origin of the ice that is most important in forming precipitation and depleting cloud water, (3) to determine the precipitation trajectories and growth histories that predominate in the overall transformation at cloud water to precipitation, and (4) to determine the effects of clouds in altering the aerosol and condensation nuclei spectra. The objectives of the mature-storm investigations include determining (1) the mechanisms by which hydrometeors evolve within mature storms, including the locations and modes of initiation as well as subsequent growth trajectories; (20) the structure and evolution or the mature storm in the context of its cellular organization, dominant scales of motions, airflow patter-:t, and factors influencing its mode ot propagation, sue-It as boundary- layer anomalies and the interaction be~~een precipitation processes and air motion; and (3) the major components of the water budget and the microphysical and dynamical factors that affect the precipitation efficiency of mature storms. A very specific atmospheric chemistry measurement program is also planned. It will include (1) surface measurements of precipitation and air quality characteristics, (2) airborne measurements of cloud water and air quality variables from air masses with nonprecipitating clouds and from mature convective storms, and (3) airborne measurement of cloud water and air quality variables <ihen the plume from the Colstrip power plant (about 100 km southwest of Miles City) is directed to'Nard the ground ne~NOrk. - 33 -