WMOD00376

• Contract/Permit #: 14-06-D-5640
• Project Name: Park Range Atmospheric Water Resources Program
• Title: Park Range Atmospheric Water Resources Program - Phase II - Parts A and B
• Date: 10/6/1967
• Weather Modification - Doc Type: Report

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direction. There is considerable scatter due, in part, to the inclusion of
stable cases. Note that the majority of the points are below the line of
one -to-one correlation. Figure 4 show s the plume mean direction plotted
against the mean Emerald wind direction. Again, there is considerable
scatter, and the plume vector is generally above the one-to-one line.
Whether the upper-air wind direction or the release-point wind best des-
cribe s the direction of plume travel depends on the individual case.

Lateral plume growth is related to the Lagrangian statistic v,2
describing the mean eddy energy. Fuquay (1964) has shown that this
quantity can be approximated by:

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,2 2 (" 2
v = u De

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and that the parameter for determining lateral plume growth is 6e U
and not 6e alone. His results with experimental data show conclusively
that 6 _:' U is supe rior to (~,_, as a predictor. He also found that the effect
\,~ ~}

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of stability on the late ral plume growth was small for his data.

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Figure 5 shows the subjective estimates of plume width plotted
against the parameter 6e u, i. e., the standard deviation of five second
wind direction values over the release period times the mean release
site wind speed. The line of be st fit from the previous season I s data
is also shown. There is considerable scatter, which is probably due,
in part, to the subjective determination of plume width, but also to the
fact that observed instantaneous lateral plume widths often change very
rapidly with time and with elevation. Figure. 6 show s plume width versus
the standard deviation of wind direction, and the scatter appears comparable
to that of Figure 5. In Figure 7, the plume width is plotted versus the
standard deviation of wind speed and an inverse relationship is indicated.
The se re sults sugge st that the diffusion problem in mountainous terrain
is so complex that it does not lend itself to statistical treatment with a
limited number of samples; each case must be studied individually.

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