WMOD00315 ‎(2)‎

• Title: Colorado River Augmentation Demonstration Program - Technical Report January 1983 - March 1985
• Date: 4/1/1986
• Weather Modification - Doc Type: Report

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871 hours

115 episodes

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12 18 24 30
EPISODE DURATION lhl

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liquid water content,
number of trips in 1 hour,
mass loading constant (0.09 g),
number of seconds in 1 hour,
cross-sectional area of probe (1.77 cm2),
and
wind speed in m/s.

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Figure 2-8. - Cumulative distributions of SLW episodes (solid line) and hours of SLW (dashed line) as a function of episode duration.
While over 50 percent of episodes were less than a 3-hour duration, 80 percent of the hours of SLW were recorded within the
episodes longer than 5 hours.

where:
LWC
N
M

5

Simplifying equation (1) results in:

LWC (g/m3) = 0.141N
5

The value of LWC in equation (2) is an hourly average and
caution must be used in its interpretation. In some cases" a
portion of the ice accreted prior to a trip may have been
deposited during the previous hour. This is highly probable,
especially in low icing rates.

The icing rate meter tripped during 103 hours of January,
February, and March 1985. This is only 7.8 percent of the
total hours in the 3-month period, and less than one-third

the frequency of events recorded by the radiometer during
the same period. The radiometer often detected SLW when
the icing rate meter did not, especially when winds were from
the south or southwest. It is improbable that the SLW was
being naturally depleted prior to reaching the icing rate meter
because the GMO is less than 2 km from the radiometer,
and at a higher elevation. More likely, the supercooled cloud
simply lay above the 70-m sensor height, which was thus
not exposed to the icing conditions. This has been observed
by personnel atop the Mesa in some cases.

(2)

A serious drawback to the icing rate meter is that it senses
at a single point and relies upon the wind, whereas the ra-
diometer sample volume is a slender cone and independent
of the wind. This suggests that such meters should be in-
stalled as far above the surface as practical 50 that they are
subjected to the maximum number of events. In addition,
amounts of rime below the instrument threshold of detection
may accrete and later sublimate, and thus never be recorded.

In northerly flow, the radiometer normally recorded SL W
concomitant with icing by the Rosemount sensor. However,

12