WMOD00416

• Title: Wintertime Cloud Systems Over the Rockies: Three Case Studies
• Date: 12/1/1980
• Weather Modification - Doc Type: Report

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periods and less often between storm events, depending upon the local

weather conditions and the type of experimental day declared, i.e.,

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transport and diffusion or microphysical studies. All raw rawinsonde

data were carefully checked and double-checked for analysis errors and

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then reduced by the Environmental Data Network System operated by the

Water and Power Resources Service, formerly known as the Bureau of

Reclamation (Po1ete, et al., 1977). The EDNS provides for various for-

mats of measured and derived meteorological parameters. For a general

description of errors inherent in all rawinsonde data, see Air Weather

Service (1955, 1974), Stringer (1972), and Wagner (1960a,b). The inher-

ent errors within the rawinsonde raw data set are acceptable in light

of the analysis to be performed.

The radar units consisted of a vertically pointing, .8 em, K band

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radar provided to COSE II by the National Oceantce and Atmospheric
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Administration (NOAA) and a CSU vertically point;ing Ku band, 1.8 cm,

radar available during COSE I and COSE II. The~ were operated through-

I

p
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out storm periods and were located at the base of the upwind edge of the

main barrier just southeast of Steamboat Springs. The criteria used to

specify "cloud" for both radars was that the power returned must be

three standard deviations above the receiver noise which was determined

separately.

Cloud tops in the first and third case studies were determined from

K band continuous fax strip chart data. Cloud top estimations from the

fax data format were subject to reduction errors so the cloud tops could

only be determined to the nearest 150 meters. Cloud top determinations

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for the second case study were determined from Ku band radar digital

data. The resolution of the Ku radar analysis is 100 meters in the