85th AMS Annual Meeting

Wednesday, 12 January 2005: 1:45 PM
Preliminary Results from a Randomized Winter Propane Seeding Experiment in Utah
James A. Heimbach Jr., UNCA, Springvale, ME; and A. B. Super
A fully-automated randomized experiment using in-cloud liquid propane releases was conducted on Utah's Wasatch Plateau during the 2003/04 winter. Detection of supercooled liquid water (SLW) cloud automatically determined the start of a 2-hr experimental unit pair, one seeded by random decision. Prior propane seeding case studies at the same location produced some obvious increases in target ice crystal concentrations and snowfall rate, but natural snowfall variability usually masked any evidence of seeding effects. This shortcoming was overcome by the randomized experiment which used high-resolution precipitation gauge observations at a few target sites with a crosswind gauge used for control. Statistical tests will be reported which are encouraging for a number of partitions based on wind direction and SLW presence.

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