WMOD00505

• Contract/Permit #: 14-06-D-5640
• Project Name: Park Range Atmospheric Resources Program
• Title: Park Range Atmospheric Resources Program - Final Report
• Date: 9/30/1969
• Weather Modification - Doc Type: Report

GRAM

V. ANALYSIS

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_ MEASURED .......-...--.. Ale TRAeKS

igure 43a.-Plume Dimensions and Pibal (pilot Ballon)
Soundings for 2 February 1965.

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te the
on the
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.itions

within about one-half hour after initial tracer dis-
persing. The mean direction of the plume is closely
related to the 11,000 feet ASL (above sea level)
wind direction and its propagation speed to the
wind speed at that altitude. The plume dimensions
and direction have little relationship to the wind
measured at the Emerald Mountain dispensing site.
The parameter (FO V-where (FO is standard devia-
tion of the lateral wind direction and V the mean
wind speed-as measured on Emerald Mountain,
appears to indicate the relative growth of the plume
with time, but its use in conventional plume predic-
tion models does not lead to usable results. The
vertical dimension of the plume is difficult to meas-
ure under quasi-operational conditions because of
restricted VFR airspace and rapid mixing of the
plume by convective action. The values of the (Fe U
value for each diffusion test are given in table 5;
equivalent values for each analysis period are also
listed. It appears that a value of (Fe U >0.5 assures
adequate dispersion of the plume.
Snow samples taken after the 25 March and 8

nboat
1965.
:le de-

.lotted
:,43d,
March
'ly op-
ced a
:adian

33

April 1965 tests reveal high concentrations of
tracer material on the ground beneath the plume.
The concentrations are often 1,000 times greater
than the minimum detectable by the laboratory
ZnS analyzer, figure 44.
Diffusion tests on 2 February, 3 February, 18
February and II March 1965 were conducted under
stable to very stable conditions-not operational
nucleating conditions. The detected plumes behave
much as predicted by theoretical models-narrow
both laterally and vertically.
Conclusion.-Under even light convective condi-
tions, artificial nuclei dispersed from Emerald
Mountain will reach and cover the target area in
high concentration if the 11,000 feet ASL wind is
between 2400 and 3000 true. Since the majority
of the Phase I winter-spring storms had associated
with them such winds, figure 45, and these storms
produced most of the precipitation, figure 46, most
of the important storms over the target area can
be nucleated artificially from Emerald Mountain.
Operational Consequence.--A single nucleating

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IR!iiiIII MEASUREO t-----f 'Ale TRACKS

Figure 43b.-Plume Dimensions and Pibal Soundings for 3
February 1965.