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Lulin Xue, Akihiro Hashimoto, Masataka Murakami, Roy Rasmussen, Sarah A. Tessendorf, Daniel Breed, Shaun Parkinson, Pat Holbrook, and Derek Blestrud

2009 in southeastern Australia is one such experiment ( Manton et al. 2011 ; Manton and Warren 2011 ). A positive, but not statistically significant, impact on precipitation by ground-based AgI seeding was found. The analyses on subsets of the longer seeding cases indicated higher significance levels being achieved. The Wyoming Weather Modification Pilot Program (WWMPP) is another recent outcome-focused randomized program ( Breed et al. 2011 ). The WWMPP is an ongoing project from 2005 that

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Xia Chu, Lulin Xue, Bart Geerts, Roy Rasmussen, and Daniel Breed

1. Introduction The main motivation for advertent weather modification remains precipitation augmentation. By 2025, an estimated 3 billion people will be subject to severe water shortages ( Black and King 2009 ). Glaciogenic cloud seeding started in the mid-1940s when scientists at General Electric Research Laboratory demonstrated that dry ice and silver iodide (AgI), which have a similar crystal structure to ice, could initiate ice in a laboratory supercooled liquid cloud. When dry ice pellets

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Lauren M. Hand and J. Marshall Shepherd

relative frequencies of different synoptic weather types. Such uncertainties highlight the need for more observational and modeling research in this area ( Dabberdt et al. 2000 ). This research takes a unique approach to examine urbanization and rainfall modification. The study uses 9 yr (1998–2006) of warm-season (June–September) mean daily rainfall accumulation obtained from both the Tropical Rainfall Measuring Mission (TRMM) ( Kummerow et al. 2000 ; Huffman et al. 2007 ) Multisatellite

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R. Giles Harrison, Keri A. Nicoll, Douglas J. Tilley, Graeme J. Marlton, Stefan Chindea, Gavin P. Dingley, Pejman Iravani, David J. Cleaver, Jonathan L. du Bois, and David Brus

November 2019, under fair weather conditions with clear skies and no appreciable local charge generation from meteorological processes. (Details of these further flights are also provided in Table 1 .) Detection of the aircraft’s charge emission was made using a Chubb JCI131 electric field mill (EFM), to measure the vertical electric field at the surface. The EFM was mounted on a 3-m-high vertical mast, separately calibrated to correct for the electric field distortion due to the presence of the

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Andrew M. Coutts, Jason Beringer, and Nigel J. Tapper

the Monash University weather station ( www.arts.monash.edu.au/ges/research/climate/weather ). The quality-controlled available data for each station were used to train the RBF network for the corresponding site’s dataset, along with the site-specific available energy balance data for the station. The RBF network tests the results and outputs an estimate value for each 0.5-h period that was either missing or screened out. The results showed an acceptable performance in generating the missing data

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National Science Foundation Staff
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Wallace E. Howell

that the filter deviceswere unable to detect IN in the SGC is not justified. REFERENCEParungo, F. P., and P. A. Allee, 1978: Rocket effluent: Its ice nucleation activity and related properties. J. Appl. Meteor., 17, 1856-1863.Comments on "Planned Weather Modification and the Severe Weather Threat in the Central High Plains" WALLACE E. HOWELLl Rural Route 3, Box 400, Golden CO 80401 31 August 1979 The weather modification

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Barbara C. Farhar

Prior to the Rapid City flood of 9 June 1972, a panel of South Dakota respondents had participated in a sociological survey on opinion about weather modification. The panel was reinterviewed after the event. Findings show that most respondents were aware that cloud seeding had occurred prior to the flood, that the majority did not attribute the flood to cloud seeding, that Rapid City area residents were no more likely than other respondents to attribute a causal link, and that the perception of the disaster as man-made is associated with increased awareness and belief that the technology is effective and decreased favorability toward the technology and toward programs. No organized opposition to weather modification has occurred in South Dakota since the flood.

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Gary L. Achtemeier

348JOURNAL. OF APPLIED METEOROLOGYVOLUME 18Planned Weather Modification and the Severe WeatherThreat in the Central High PlainsGARY L. AcBTEMEIERJihnois SSa~e Wok, Survey, Urbana 61.l'Ol(Manuscript received 20 July 1978, in final form 15 November 1978)ABSTRACTOperational and experimental convective cloud-seeding projects are often planned without regard to thenumber of seeding-opportunity days that can be lost because of the need to suspend operations during thethreat of severe weather. June

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Stanley A. Changnon and W. Henry Lambright

The development of weather modification requires resolution of a number of scientific questions. To resolve them necessitates field experiments that frequently extend over many years and cost millions of dollars. These projects usually are highly visible to the scientific community and, often, to the public as well. Weather modification and similarly risky technical efforts requiring field research typically involve a large number of scientists with varying interests and incentives. As they seek to resolve certain scientific controversies, the projects also generate other conflicts that are organizational, budgetary, and sometimes public. The scientific conflicts cannot be separated from these controversies in their environment. Solving the one kind requires dealing with the others.

To learn how such projects should be designed, conducted, and evaluated, we studied four major weather-modification projects and determined the origin and resolution of their scientific, management, and policy controversies. The assessment revealed that to conduct major field experiments concerning scientific topics viewed as controversial within the scientific community is extremely difficult due to the multifaceted nature of the scientific controversy. The major scientific controversies were a result of six factors, including 1) proceeding with an inadequate scientific knowledge base; 2) a flawed project-planning process; 3) differing views between funding agencies and project scientists; 4) lack of continuing commitment by the principal agency conducting the experiment; 5) changes in project directors; and 6) poor performance by project scientists.

This study reveals that, in order to minimize scientific controversy, certain procedures should be followed that impact on the environment of the project as well as the intrinsic science performed therein. First, an initial, in-depth assessment of the need for the proposed project vs the state of scientific readiness must be conducted using the most credible scientists in the field. Then, the most knowledgeable scientists should be involved in the planning process, and third, the major funding entity—usually the federal government—must make a commitment adequate in both time and resources. The selection of a single institution clearly committed to the study of scientific issues to be investigated is a critical fourth factor, and those selected as project directors must have demonstrated scientific and management skills. Finally, a project needs thorough and frequent oversight by a knowledgeable and prestigious group. Ideally, those involved in the planning would have strong input in the evaluation.

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