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<br />RECENT FINDINGS FROM THE <br />SIERRA COOPERATIVE PILOT PROJECT (SCPP) <br /> <br />by <br /> <br />John D. Marwitz <br />University of Wyoming <br /> <br />Arnett Dennis reviewed the past and present weather <br /> <br />modification programs in California. <br /> <br />The operational seeding <br /> <br />projects (such as the King's River, Lake Almanor and Santa <br /> <br />Clara County) have been evaluated based on runoff with <br /> <br />increases estimated at 4 to 5%. The Santa Barbara Project was <br /> <br />randomized and the increased precipitation appears to result <br /> <br />from a dynamic seeding effect since there was a substantial <br /> <br />pressure perturbation in the surface pressures on seeded <br /> <br />rainbands. <br /> <br />Project CENSARE was a physical studies' project <br /> <br />with some seeding. CENSARE identified needles as the dominant <br /> <br />crystal habit. Flights by DRI in their B-26 aircraft revealed <br /> <br />that convective clouds had lots of lightning and supercooled <br /> <br />water. The SCPP was developed by the Bureau of Reclamation in <br /> <br />the mid-1970's in response to a request by the State of <br /> <br />California and the Bureau's Western Regional Office. <br /> <br />Dr. John Marwitz reviewed the physical studies which have <br /> <br />occurred in SCPP. <br /> <br />SCCP has had a field season during every <br /> <br />season but one since 1976. <br /> <br />There has been a steady increase <br /> <br />and improvement in instrumentation with the key observing <br /> <br />equipment <br /> <br />being radar (both conventional and <br /> <br />Doppler), <br /> <br />instrumented aircra~t, precipitation gages, rawinsondes and <br /> <br />microwave radiometers. <br /> <br />1 <br />