|
<br />JULY 1988
<br />
<br />RAUBER ET AL.
<br />
<br />827
<br />
<br />.,
<br />
<br />associated with the absence of water saturated condi-
<br />tions locally on the seedline. The high ice particle con-
<br />centrations found on the seedline suggested that sub-
<br />water saturated conditions may have been due to over-
<br />seeding. It appeared from the data that sub-water sat-
<br />urated conditions prevented the development of nee-
<br />dlelike habits at these temperatures.
<br />A case study comparing radar echo evolution in
<br />seeded cloud regions with predicted particle trajectories
<br />was presented. In general, good agreement between ra-
<br />dard echo evolution and predicted particle trajectories
<br />was obtained. The predicted falltime was nearly iden-
<br />tical to the radar results, but the predicted fallout lo-
<br />cation differed by 5 km.
<br />In most cloud seeding applications, target areas are
<br />oflimited extent and the opportunities for cloud mod-
<br />ification are limited in duration. In the Sierra Nevada
<br />region, these problems are compounded by the rapid
<br />evolution and complex structure of many storm sys-
<br />tems. To conduct successful seeding operations, it is
<br />important that the best estimate of the appropriate
<br />place to seed is available in a short time frame. The
<br />methods described in this paper represent one attempt
<br />to accomplish this task. As targeting methods continue
<br />to be developed and refined, better evaluations of the
<br />effects of weather modification should become avail-
<br />able. With refined targeting techniques, the role of
<br />weather modification in the management of water re-
<br />sources can be more effectively assessed.
<br />
<br />Acknowledgments. This work was sponsored by the
<br />Department ofInterior, Bureau of Reclamation under
<br />Contracts 9-07-85-Y0021, 4-CR-81-03860 and 7-07-
<br />83- Y0008. The authors would like to thank all SCPP
<br />participants for their contributions to this paper. Par-
<br />ticular thanks to the staff ofthe University of Wyoming,
<br />who provided data and expertise associated with the
<br />King Air. A special acknowledgement is due to the
<br />staff of Electronic Techniques, Inc., particularly Ms.
<br />Carol Wilcox, who drafted the figures and typed the
<br />manuscript, and Mr. Arunas Kuciauskas, who devel-
<br />oped software to display radar data and targeting cal-
<br />culations.
<br />
<br />I
<br />~.
<br />
<br />REFERENCES
<br />
<br />Anthes, R. A., and T. T. Warner, 1978: Development ofhydrody-
<br />namic models suitable for air pollution and other mesometeo-
<br />rological studies. Mon. Wea. Rev., 106, 1045-1078.
<br />Brown, S. R., 1970: Terminal Velocities ofIce Crystals. Atmos. Sci.
<br />Paper No. 170, Colorado State University, Fort Collins, Colorado
<br />80523.
<br />Browning, K. A., and G. A. Monk, 1982: A simple model for the
<br />synoptic analysis of cold fronts. Quart. J. Roy. Meteor. Soc..
<br />101, 893-900.
<br />Bureau of Reclamation, 1985: Design of a randomized exploratory
<br />fixed target experiment on widespread winter orographic clouds.
<br />Bureau of Reclamation, Div. of Atmos. Res. Research, D-1200,
<br />Box 25007, Denver, CO 80225, 52 pp.
<br />Clark, T. L., 1977: A small scale dynamic model using a terrain
<br />following coordinate transfonnation. J. Comput. Phys., 24, 186-
<br />215.
<br />
<br />Cooper, W. A., and R. P. Lawson, 1984: Physical interpretation of
<br />results from the HIPLEX-I experiment. J. Climate Appl. Me-
<br />teor., 23, 523-540.
<br />Cornford, S. G., 1965: Fallspeeds of precipitation elements. Quart.
<br />J. Roy. Meteor. Soc., 91,91-94.
<br />Davis, C. 1., 1974: Ice nucleating characteristics of various Agl aero-
<br />sols. Ph.D. dissertation, University of Wyoming, 259 pp.
<br />DeMott, P. J., W. G. Finnegan and L. O. Grant, 1983: An application
<br />of chemical kinetic theory and methodology to characterize the
<br />ice nucleating properties of aerosols used in weather modifica-
<br />tion. J. Climate Appl. Meteor., 22, 1190-1203.
<br />Deshler, T., and D. W. Reynolds, 1987: The evolution of artificially
<br />nucleated ice crystals in shallow orographic winter clouds: Two
<br />case studies. 11th Conf on Weather Modification, Edmonton,
<br />Am,:r. Meteor. Soc., 34-39.
<br />Elliott, R. D., 1981: A seeding effects targeting model. Pre prints of
<br />Eighth Conf on Inadvertent & Planned Weather Modification,
<br />Reno, Amer. Meteor. Soc., 28-29.
<br />-, and J. O. Rhea, 1984: Comparison of observed and predicted
<br />model winds over an orographic barrier. Proc. Ninth Weather
<br />Modi! Conf, May 21-23, Park City, Amer. Meteor. Soc., 83-
<br />84.
<br />F1ueck, J. A., 1982: Comparative experimentation: Some principles
<br />and prescriptions. Teaching of Statistics and Statistical Con-
<br />sulting, J. Rustagi and D. Wolfe, Eds., Academic Press, Inc.,
<br />433--463.
<br />Fukuta N., and A. S. Wang, 1984: The studies of growth rates of ice
<br />crystal at different temperature and ice supersaturation. Proc.
<br />Ninth Int. Con! Cloud Physics. Tallinn, Estonia, USSR. 183-
<br />186.
<br />Gordon, G. L., and J. D. Marwitz, 1986: Hydrometeor evolution in
<br />rainbands over the California valley. J. Atmos. Sci., 43, 1087-
<br />1100.
<br />Hallett, J., and B. J. Mason, 1958: The influence of temperature and
<br />supersaturation on the habit of ice crystals grown from the vapor.
<br />Proc. Roy. Soc. London, A247, 440-453.
<br />Heggli, M., 1986: A ground based approach used to determine cloud
<br />seeding opportunity. Tenth Con! on Weather Modi!, Arlington,
<br />Am,:r. Meteor. Soc., 64-67.
<br />-, and D. W. Reynolds, 1985: Radiometric observations of su-
<br />percooled liquid water within a split front over the Sierra Nevada.
<br />J. Climate Appl. Meteor., 24, 1258-61.
<br />Heggli, M. F., R. M. Rauber and J. B. Snider, 1987: Field evaluation
<br />of a dual-channel microwave radiometer designed for measure-
<br />ments of integrated water vapor and cloud liquid water in the
<br />atmosphere. J. Atmos. Oceanic Technol. 4, 204-213.
<br />Heymsfidd, A., 1982: A comparative study of the rates of develop-
<br />ment of potential hail embryos in the High Plains storms. J.
<br />Atmos. Sci., 39,2867-2897.
<br />-, 1987: Aggregates as embryos in seeded clouds. Precipitation
<br />Enhancement-A Scientific Challenge. Meteor. Monogrs. No.
<br />21 and No. 43, Amer. Meteor. Soc., 33-41.
<br />-, and J. C. Pflaum, 1985: A quantitative assessment of the ac-
<br />curacy of techniques for calculating graupel growth. J. Atmos.
<br />Sci., 42,2264-2274.
<br />Hobbs, P. V., 1978: Organization and structure of clouds and pre-
<br />cipitation on the mesoscale and microscale in cyclonic storms.
<br />Rev. Geophys. Space Phys., 16,741-755.
<br />Huggins, A. W., and A. R. Rodi, 1985: Physical response of convective
<br />clouds over the Sierra Nevada to seeding with dry ice. J. Climate
<br />Appl. Meteor., 24, 1082-1098.
<br />-, R. M. Rauber, T. W. Lee, A. P. Kuciauskas, G. L. Hemmer
<br />and C. J. Wilcox, 1986: SCPP Meteorological and Statistical
<br />Support, Interim Progress Rep. 1985-86. [Available from Bureau
<br />of Reclamation, Division of Atmospheric Resources Research,
<br />D-1220, Denver Federal Center, Denver, CO 80225.]
<br />Humphries, J. H., 1985: Applications of an airborne optical array
<br />probe for ground.based microphysical observations. J. Atmos.
<br />Oceanic. Technol., 2,253-259.
<br />Kajikawa, M., 1971: A model experimental study on the falling ve-
<br />locity of ice crystals. J. Meteor. Soc. Japan, 49, 367-375.
<br />
|