WMOD00412

• Title: Final Report on Utah Cloud Seeding Experimentation Using Propane During the 2003/04 Winter
• Date: 3/1/2005
• State: UT
• Weather Modification - Doc Type: Report

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A tower was installed aboul6 In southwest (upwind) orlhe center dispenser as also sho....n in the figure.
Sensors on the 6 m lower included a hetucd Ilydro- Tech anemometer and wind vane, each sel a little
above the lo\\cr top. an air temperature sensor. Goodrich icing sensor and. aOer 17 February 2004. a
Rosemotlnl icing sensor. The same dala logger at the central dispenser recorded all the to\\er sensor
observations at I mill intervals. This data logger also controlled the three propane displ:nscrs. releasing
propane for exactly 40 min. or nothing if a placebo EU was dl."Clared. whenever Goodrich sensor icing
exceeded a prcdctcnnincd rale over a 10 mill interval. Two-way communication ""llh the HAS was b)-'
radio link 10 Mount Pleasant. UT. in the Sanpete Valley and Internet beyond that. Fig. ] 0 ~ho\\s the
southeast propane dispense-r. during a below-cloud base relca.'\C for demonstration purposes. Upper
por1ions of the Wa.~lch Plateau are in the background with the view toward the eas!.

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Fig. 10. South~asl propane dispenser at lIAS during a test rc1eas~ with \liew loward the Mluth~asl.

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6c.2.. ProMem.f with liAS Icing S~'nWJr.~

A Goodrich (previous]y Rose-mount) t\.1odel 872F I icing rate- sensor, similar 10 the freeling rain sensors
used on the national network of Automated Surface Observing S)'stem <ASOS) \\eather stations. was
purchased for the projcct as a kc)' instrument. A diagram oflhis sensor is sho\\n in Fig. II. Its function
wa.'i 10 monitor the rale of icing and dcc]are the beginning of each experimental unit pair once a
predelennined icing rate had been reached or exceeded. Because of delays associated wilh funding
a....ailability and other problems. the Goodrich icing. sensor was nol operational on the HAS to....er unlillO
December 1003. Meteorologists had m.'Cn on location during ]ate November to help with installation of
rnostlield instruments but the Goodrich sensor arrived ancr Iheir field trip. Cost considerations resulted
in none oflhe mcteorologists returning to the tie]d aller the icing scnsor was inslalled. Installalion
instructions were not included wilh the unit. The icing sensor is odd shaped in that the square electronics
hox and attached cooling ....anes must be tilted at 45 deg from thc \'er1ical for the I inch long b)' 1/4 inch
diameter sensing rod to lle properly poillled toward the lenith. The 00\ wa'i initially mounted
horizontally and vt:'r1icalJy \\hich placed the sensing rod 45 deg olfvcr1ical. The unit wa'i installed on a

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