Investigations of the Targeting of Ground-Released Silver Iodide in Utah Part II: Aircraft Observations

Authors

  • Arlin B Super Bureau of Reclamation Denver, CO
  • Arlen W Huggins Bureau of Reclamation Denver, CO

Abstract

As part of a cooperative research program between the Utah Division of Water Resources, the National Oceanic and Atmospheric Administration, and the Bureau of Reclamation, a series of aircraft missions was flown to track silver iodide plumes in the Utah operational cloud seeding program. Both valley floor and canyon mouth generator sites were tested using releases of sulfur hexafluoride tracer gas and silver iodide. Optically-tracked Airsondes provided supporting wind and stability data. Five missions were flown under atmospheric conditions that either simulated, or were the beginning of, the prefrontal phase of typical Utah winter storms. The silver iodide and tracer gas were confined to the lower atmosphere during four flights and were not transported over the intended mountain barriers. The plumes did cross the Wasatch Plateau during part of the fifth sampling mission. Ice nucleus concentrations were estimated from the tracer gas measurements of the fifth mission for typical supercooled liquid water temperatures. These estimates indicated that limited ice crystal concentrations would be formed with the generators and seeding agent currently used in Utah.

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Scientific Papers