WMOD00438

• Title: HIPLEX: A Cooperative Program on Rain Augmentation in the High Plains
• Date: 6/1/1984
• Weather Modification - Doc Type: Report

7-2090 (4-81)
Bureau at Reclamation

TECHNICAL REPORT STANDARD TITLE PAGE

1. REPORT NO. 12. GOVERNMENT AC:C~5SI0N NO. . 3. RECIPIENT'S CATALOG NO.
4. TITLE AND SUBTITLE S. REPDRT DATE
HIPLEX: A Cooperative Program on Rain June 1984
Augmentation in the High Plains 6. PERFORMING ORGANIZATION CODE
(Final Report)
7. AUTHOR(S) 8. PERFDRMING ORGANIZATION
A. S. Dennis, E. W. Holroyd III.W. E. Howell REPORT NO.
D, A. Matthews, B. A. Silverman, A. B. Super
9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. WORK UNIT NO.
Bureau of Reclamation. Division of Atmospheric
Resources Research. Denver Federal Center. 11. CONTRACT OR GRANT NO.
Engineering and Research Center, Denver, Colo.
13. TYPE OF REPORT AND PERIOD
COVERED
12. SPONSORING AGENCY NAME AND ADDRESS
Final Report
Same
,
14. SPONSORING AGENCY CODE
USBR
15. SUPPLEMENTARY NOTES
Microfiche and/or hard copy available at the Engineering and Research Center. Denver, Colo.
Editor: mjc
16. ABSTRACT
HIPLEX (High Plains Cooperative Program) was a cooperative effo,t by the Bureau of Reclamation, other Federal agen,
cies. the Canadian Government. and State and local government agencies to reduce scientific uncertainties associated
with attempts to increase growing season rainfall in the High Plains by seeding summer convective clouds.
HIPLEX involved field prOjects at Big Spring. Texas; Goodland. Kansas; and Miles City. Montana; as well as supporting
studies in short-range forecasting, cloud modeling, forage and crop yields. agricultural economics, and environmental
matters. Large amounts of data were gathered by radar sets, instrumented aircraft rawinsondes. and other instruments.
Data collection, reduction, and analysis were automated as far as resources allowed. Calibration seeding trials were
conducted in Texas and Montana. The Kansas experiments were halted after it became apparent that the severe
weather associated with Kansas storms would limit seeding opportunities. The decision was made to concentrate funds
and equipment in Texas and Montana. A randomized experiment (HIPLEX-1) was conducted on isolated cumulus con-
gestus clouds around Miles City 1979,80.
HIPLEX,l was a unique experiment that attempted to document the steps In a phYSical hypothesis linking dry ice
seeding of small to moderate sized cumulus clouds to increased rainfall at cloud base. It was hypothesized that ice
crystals produced by seeding wou}~ grow by diffusion, reach their riming threshold within 5 rylinutes, grow into graupel
in another 10 minutes or so. and melt to rain during their fall to the ground. The results confirmed only the first steps
of the process up to about the onset of riming. The liquid water concentration decreased so rapidly in many of the
short-lived test clouds that graupel could not grow to precipitation size. Aggregate snowflakes were produced Iii some
of the seeded clouds.
When experimentation resumes, it is recommended that the seeding trials proceed to the larger clouds, with appro-
priate consideration made for the covariates. In 1980 and 1981, data from an experimental network of automatically
reporting weather stations were fed into computers for real-time analysis. The results pointed the way to improved
short-range forecasts of convective clouds and storms, and therefore, to more carefully controlled experiments on the
larger convective clouds in the future.
Sludies of the value of additional preCipitation (from future operational proJects) suggesl that crop and rangeland yields
increase as increments of precipitation increase. The net benefits to the High Plains were projected to be in the millions
of dollars per year. The economic benefits to be gained justify continued experimentation to develop an effective pre-
cipitation enhancement technology.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCR IPTORS-- / weather modification/ cloud seeding/ cloud physics/ cloud modifica-
tion/ water resource management/ statistical analysis/ cumulus clouds/ meteorological
instruments/ airborne equipment! data collection/ climatology/ environmental effects/ eco-
nomic impacts/ social aspects/ rainfall! atmospheric research/ precipitation/ induced precip-
itation/ radar
b. IDENTIF IERS-- HIPLEX/ High Plains/ Montana/ Kansas/ Texas
c. COSATI Field/Group 04B COWRR: 0402.1 SRIM:
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