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<br />3.10.1 Experimental unit declaration <br /> <br />An experimental unit will be declared when clouds III the target area pair satisfy the <br />following qualification criterion: <br /> <br />Multiple convective clouds with at least 1 kilometer, but no more than 3 kilometers, <br />in depth are present in both target areas. The presence of one or two isolated <br />convective clouds at least 1 kilometer in depth in each area does not satisfy this <br />criterion, but a line of clouds in each area with only a few towers 1 to 3 kilometers in <br />depth does satisfy this criterion. <br /> <br />3.10.2 Flight procedures <br /> <br />The flight and seeding procedures to be implemented in the warm cloud seeding <br />demonstration project are described in "Volume 3 -Demonstration Project Operations Plan" <br />of this PASA Final Report. Two CASA aircraft carry out seeding in the target area randomly <br />selected for treatment. The two CASA aircraft fly together during seeding operations, <br />simultaneously seeding at two prescribed altitudes. Thus, the seeded clouds will receive a <br />double dose of CaCl2 particles. <br /> <br />The AeroCommander aircraft will be used to confirm whether clouds in the two target areas <br />meet the warm cloud seeding qualification criteria, and to make preseeding and postseeding <br />measurements. <br /> <br />3.11 Projected Duration of the Demonstration Project <br /> <br />Sample size estimates for the warm cloud demonstration project are discussed in detail in <br />appendix E and summarized here. Assuming, for example, that seeding increases rainfall <br />by 10 percent [SMF (seeding multiplicative factor) = 1.10], table 3.1 gives the sample sizl~s <br />required to achieve probabilities of detection of 0.80 and 0.90 at a significance level of 0.05. <br /> <br />Table 3.1. - Estimation of the number of samples that will be required in the warm cloud seeding <br />demonstration project to reach a statistical significance level of 0.05 for a power of 0.80 and 0.90, <br />assuming an increase in rainfall caused by seeding of 10 percent. <br /> <br />East <br /> <br /> Sample Size for Seedin~ Model <br />Power Multiplicative Mult + Add <br />0.80 93 75 <br />0.90 144 102 <br />0.80 99 64 <br />0.90 195 104 <br /> <br />Target Pair <br /> <br />West <br /> <br />These results indicate that obtaining the required number of samples would take from 2 to <br />3 years, assuming that 60 seeding opportunities occur per year and that all are successfully <br />implemented. Obtaining the required number of samples will likely take 4 to 5 years (a <br />conservative estimate) because the number of opportunities is likely to vary and some seeding <br />opportunities will be missed because of errors in execution or equipment failures. It is <br />emphasized that the number of samples will determine the duration of the experiment. <br /> <br />30 <br />