WMOD00453

• Project Name: Park Range Atmospheric Water Resources Program
• Title: Park Range Atmospheric Water Resources Program - Phase I
• Date: 1/1/1967
• Weather Modification - Doc Type: Report

V. ANALYSIS

Pl8AL POINTS
2 FEB. 1965

. \
.\ .
. ,j
I. ,

/

/

~ PREDICTED

_ MEll.SUREO

......-----. A./e 'TRA.CKS

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

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 (TO V-where (TO is standard devia-
t Ion of the la teral wind direction and V the mean
ind speed-as measured on Emerald Mountain,
a pears to indicate the relative growth of the plume
ith time, but its use in conventional plume predic-
t on models does not lead to usable results. The
v rtical dimension of the plume is difficult to me as-
u e under quasi-operational conditions because of
r stricted VFR airspace and rapid mixing of the
p ume by convective action. The values of the (Te U
v lue for each diffusion test are given in table 5;
e uivalent values for each analysis period are also
Ii ted. It appears that a value of (Te U >0.5 assures
a equate dispersion of the plume.
Snow samples taken after the 25 March and 8

33

April ] 965 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 11 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

Ie mi R.
- -------------

PIBAL POINTS
3 FEB. 1965

~

8-1300' \
c.1500' "-
D - ..00' ""-

OAK CREEK

I
,.

.

./

~ PREDICTED

_ MEASURED

~ A./e TRACKS

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