WMOD00293

• Title: Summary of the NOAA/Utah Atmospheric Modification Program: 1990-1996
• Date: 9/1/1998
• State: UT
• Weather Modification - Doc Type: Report

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..- .."";';'fi'E f)CnfT;PD,odu MEN TAT ION PAGE Form Approved
OMS No. 0704-0188
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Report 10704-0188), Washington DC 20503.
1. AGENCY USE ONL. Y (Leave Blank) 2. REPORT DATE 3. REPORT lYPE AND DATES COVERED
September 1998 Final
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4. TITL.E AND SUBTITL.E .. , , 5. FUNDING NUMBERS
Summarv .of the NOAA/Utah Atmospheric Modification ProQram: 1990-1996
6. AUTHOR(S) ,
Arlin B. Super
7. PeRFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
REPORT NUMBER
Bureau of Reclamation
Water Resources Research Laboratory R-98-07
, Technical' service' Center \
Denver, Colorado
9. SPONSORINGlMONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
Same
11. SUPPL.EMENTARY NOTES
Hard coov available at the Technical Service Center, Denver, Colorado
12a.,DISTRIBUTIONlAVAILABIL.1TY STATEMENT 12b. DISTRIBUTION CODE
Available from the National Technical Information Service, Operations Division,
5285 Port Roval Road, Sorinafield, Virainia 22162
13. ABSTRACT (Maximum 200 words)
This final report summarizes physical investigations into the artificial nucleation ("seeding") of winter mountain clouds in central
Utah during 1990-96. Program goals were to evaluate the effectiveness of the Utah operational cloud seeding program and to
recommend improvements. Field programs employed a wide variety of instrumentation systems. Sophisticated numerical
modeling was used in conjunction with the observational programs. Amounts and distributions of SLW (supercooled liquid water)'
cloud were investigated, as was transport and dispersion of ground-released seeding agents and tracer gases. Several
experiments directly monitored ice crystals and snowfall rates resulting from either silver iodide (Agl) or liquid propane seeding.
Results showed frequent SLW in excess of natural conversion to snowfall, suggesting significant seeding potential. The SLW
was concentrated near the terrain where temperatures were relatively warm. When valley-released Agl was transported to cloud
levels, resulting ice crystal formation was usually too limited for significant snowfall augmentation. However, marked
enhancement of ice crystal concentrations and snowfall rates resulted from a number of high altitude releases of both Agl and
liquid propane. Propane seeding was effective within even slightly supercooled cloud. Several recommendations were given for
improving the operational seeding program's effectiveness.
14. SUBJECT TERMS 15. NUMBER OF PAGES
artificial nucll;lation! cloud physics! cloud seeding! ice crystals! orographic clouds! precipitation
augmentation! silver iodide! snow augmentation! supercooled liquid water! transport and dispersion! 16. PRICE CODE
Wasatch Plateau. UTI weather modification!
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17. SEC'URllY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF
O~ REPORT OF THIS PAGE OF ABSTRACT ABSTRACT '
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