WMOD00317

• Contract/Permit #: 14-06-D-6999
• Project Name: CAWRP
• Title: Cascades Atmosphere Water Resources Program - Volume I
• Prepared For: US Department of the Interior Bureau of Reclaimation
• Date: 7/1/1970
• Weather Modification - Doc Type: Report

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SECTION 2

GROUND INSTRUMENTATION AND PROCEDURES

2.1 Network of Stations

During the winter of 1970-71, measurements were made at twelve ground

stations straddling the Cascade Divide over an area which is shown in Fig. 2.1.
Five of these stations (Alpental base, Keechelus Dam, Stam?ede Pass, Kachess
Dam and Greenwater) were manned during designated "storm days." The other

stations had automatic sensors which could run unattended for about a week.

A small CW Doppler radar was operated at Keechelus Dam and rawinsondes were

launched and tracked from Greenwater. The University of Washington in Seattle

served as a control center to which data and information were relayed by radio

from the manned stations as well as from the aircraft.

The types of measurements made at each of the ground stations are listed

in Table 2.1 Comments on some of the instruments and techniques are given

below.

2.2 Precipitation

Three different instruments were used to measure precipitation: weighing

buckets, tipping buckets and optical snow-rate sensors. The most standard of

these instruments is the weighing bucket precipitation gauge (Science Assoc.,

Model No. 551). These were equipped with a 24-hour clock drive and could run

unattended for about a week. Solid precipitation is melted by an ethylene

glycol-type anti-freeze. The instrument can resolve 0.02 inches of

precipitated water and has a time resolution of about 5 minutes. The heated,

tipping bucket precipitation gauge (manufactured by E. Bollay Assoc.) has an

orifice 0.45 m2 in area and, as supplied by the manufacturers, it can resolve