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<br />A Statistical Reanalysis of the ae?licat~d Cli~ax r and II <br />Yinte~ci~e O~og~a?hic Cloud Seeding Experiments <br /> <br />1 ' Z <br />Paul W. Mielke. Jr. . Clenn~. Brier-, Le~is o. Grant, <br /> <br />v l' Z.J d 1 R . Z <br />Gerald J. nU vey ,an Pau N. osenzueLg <br /> <br />Colorado State University, Fort Collins, CO 80523 <br /> <br />Abstract <br /> <br />A reanalysis of the Climax I and II experiments is described. The <br /> <br />conc~~ proopclng chis reanalysis is a su~gestiQn arising froa Colorado <br /> <br />State University analyses of extended area effects. Those analyses suggested <br /> <br />a region-vide p.ttern of precipitation that, by chance, may have favored the <br /> <br />rando~y selected seeding days for some of the ieportant ~teorological <br /> <br />partitions used in earlier analyses. In order to address this concern, this <br /> <br />reanalysis employs excellent covariate relationships developed before the <br /> <br />1n1tiation of Climax II and which account for over half of the targe:t <br /> <br />variability for mosc meteorological partitions of major interest (e.g.. <br /> <br />warQ 500-mb temperatures and southuest 70o-Qb wind directions). The <br /> <br />.tatistical evidence of seeding induced increases associated vith this <br /> <br />reanalysis Is generally much stronger than the previous analysis which did <br /> <br />not uci1ize the covariate data. For example, the joint one-sided Yllcoxon <br /> <br />test statis~c P-value for testing the null hypotbesis that seeding did not <br /> <br />~nduce a preclpieation increase during warm 500-mb temperatures of the <br /> <br />Climax I and II experiments is noW 0.0013 compared to 0.0550 with the <br /> <br />previous analysis Yh~ch did not u~ilize the covariate data. However, the <br /> <br />reanalysis also indicates that previous estiln.1.tes of increases attr:ibuted <br /> <br />to seeding based strictly on ratios of seeded to non-seeded precipitation <br /> <br />amount means are apparently too large. For example, the e5ti~ted <br /> <br />precipitation increase af the co~bined Climax I and II data for the ~arm <br /> <br />500-mb temperature partition is reduced from 41 ?ercent to 25 percertt when <br /> <br />usln; th~ full set of d~C3 ns ~oplo~~d in chis reanal~sis. <br /> <br />-19- <br /> <br />F <br /> <br />> <br />...i <br /> <br />A-1l-3 <br />