WMOD00275

• Contract/Permit #: 85-5071
• Title: Cooperative Weather Modification Research Program - 1985 Analysis Plan
• Date: 1/1/1985
• State: UT
• Weather Modification - Doc Type: Report

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Experiment 7: Relation elf liquid water and precipitation particle
growth

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Lead Scientist: Kenneth Sassen, UU

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Participating Scientists: Alexis B. Long, Patricia A. Walsh, DRI
Robert A. Kropfli, William R. Moninger,
Jack B. Snider, Taneil Uttal, WPL
Lewis O. Grant, Robert M. Rauber, CSU
Norihiko Fukuta, UU
Thomas J. Henderson, AI

The objective of the analysis is to describe the physical inter-

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dependence of precipitation particle growth and the amount and distribu-

tion of supercooled liquid water.

Data from the full complement of

instrumentation will be studied.

The Iidar data will be used as follows.

Time-height plots of

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I inear depolarization ratio <5 will be examined in a search for regions

of cloud where liquid water' is present.

The ratios in appropriate

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neighboring regions of the cloud will then be examined for evidence that

the liquid water is (or is not) being used in the precipitation process.

If a liquid water region disappears with time then a search will be made

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for any correlating effect in <5 in neighboring regions of the cloud.

I nterpretation of the Iidar data in these ways will of necessity require

supporting radar and radioml~ter data on cloudy regions upwind of the

Iidar beam.

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The radar and radiometer data will be jointly examined.

If the

radiometer liquid water is important for growth a positive association of

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it and radar reflectivity fclctors observed later in time should be

expected.

If growing precipitation particles feed on the liquid water

then a negative association of the two variables measured simultaneously

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should be expected eventually.

The time lag between the radar and

radiometer data should thus be important in the analysis.

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