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<br />2006 <br /> <br />JOURNAL OF CLIMATE AND APPLIED METEOROLOGY <br /> <br />VOLUME 22 <br /> <br />TABLE II. Ridge temperature partitions for colder days during the 1969-70 winter using the single Gallatin Range gage for control. <br />Probabilities and double ratios are for 3 zones of Fig. I. <br /> <br /> Experimental <br /> days Zone I Zone 2 Zone 3 <br />Range <br />(0C) All s/ns* W** MRPP D.R. W MRPP D.R. W MRPP D.R. <br />~ -7.0 47 27/20 0,04 0.04 2.06/2.37 0.30 0.35 2.44/3.25 0.32 0.28 1.43/2.03 <br />~ -9.0 41 24/17 0.08 0.10 1.93/2.25 0.16. 0,26 3.17/4.50 0.34 0.33 1.37/2,50 <br />~ -11.0 29 16/13 0.Q7 0.09 2.01/3.56 0.41 0.29 2.08/6.75 0.42 0.28 1.46/0.00 <br /> <br />* s-seeded/ns-nonseeded. <br />** Wilcoxon. <br /> <br /> <br />that only the southern seeding site was operated during <br />the winter of 1969-70, prior to the 1970-71 and 1971- <br />72 seasons analyzed thus far. That winter's data set is <br />not totally compatible with the two latter winters for <br />other reasons as well; namely, the Gallatin Range gage <br />was the only available control, somewhat different <br />seeding generators were used, and AgI was complexed <br />with NaI in 1969-70 rather than with NH4I as used <br />later. However, with the realization that the Gallatin <br />Range gage appeared to be a suitable control by itself, <br />it was decided to apply the previous analysis procedures <br />to the 1969-70 winter's data. It should be noted that <br />one less gage was operated during the 1969-70 winter <br />in Zone 1 and also in Zone 3, reducing the number <br />of gages in the respective zones to 11 and 6. <br /> <br />Seeding Sites <br /> <br />5000 <br /> <br />Table 11 shows the resulting probabilities and double <br />ratios for the colder cases during 1969-70. It is seen <br />that relatively low probability values occur in Zone 1, <br />again suggesting a seeding effect in the intended target <br />area. Low probabilities did not occur farther down- . <br />wind. However, reference to Tables 4 and 11 shows <br />that individual analysis of each of the three separate <br />winters of the BRE sugggested increased target area <br />precipitation associated with seeding when Ridge tem- <br />peratures were ~ -90C. <br />It is interesting to examine the 1969-70 spatial dis- <br />tribution of probabilities across the three zones of Fig. <br />1, particularly since only one seeding site was used. <br />This was done by calculation of the Wilcoxon prob- <br />ability and mean double ratio for each gage in the <br /> <br />M <br />2.11 <br /> <br />5000 <br /> <br />.26 (( <br />~ ooIJ -. <br />~o <br /> <br />KEY <br /> <br />2000 it Contour. Shown <br />g Wilcoxon ProbabilIty <br />Y Y Double Ratio <br /> <br />Scali (kilometer.) <br />o 10 <br />------ <br /> <br />FIG. 4. Map of Wilcoxon probabilities and mean double ratios for the 41 1969-70 winter days with Ridge temperature ~ -9.00c. ' <br />