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Neil G. Towery
,
Griffith M. Morgan Jr.
, and
Stanley A. Changnon Jr.

Abstract

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Neil G. Towery
,
Stanley A. Changnon Jr.
, and
Griffith M. Morgan Jr.

The characteristics of commonly used surface hail instruments are reviewed and instruments evaluated. The instruments evaluated have been classified into two major categories: integrating and recording. The integrating sensors are relatively inexpensive and provide certain useful hail data. The recording sensors are much more expensive but provide more useful data including time of hail. The review includes the principles of operation, types of data obtained, operational advantages and disadvantages, and approximate cost of each type of instrument.

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Stanley A. Changnon
,
Roger A. Pielke Jr.
,
David Changnon
,
Richard T. Sylves
, and
Roger Pulwarty

Societal impacts from weather and climate extremes, and trends in those impacts, are a function of both climate and society. United States losses resulting from weather extremes have grown steadily with time. Insured property losses have trebled since 1960, but deaths from extremes have not grown except for those due to floods and heat waves. Data on losses are difficult to find and must be carefully adjusted before meaningful assessments can be made. Adjustments to historical loss data assembled since the late 1940s shows that most of the upward trends found in financial losses are due to societal shifts leading to ever-growing vulnerability to weather and climate extremes. Geographical locations of the large loss trends establish that population growth and demographic shifts are the major factors behind the increasing losses from weather–climate extremes. Most weather and climate extremes in the United States do not exhibit steady, multidecadal increases found in their loss values. Without major changes in societal responses to weather and climate extremes, it is reasonable to predict ever-increasing losses even without any detrimental climate changes. Recognition of these trends in societal vulnerability to weather-climate extremes suggests that the present focus on mitigating the greenhouse effect should be complemented by a greater emphasis on adaptation. Identifying and understanding this societal vulnerability has great importance for understanding the nation's economy, in guiding governmental policies, and for planning for future mitigative activities including ways for society to adapt to possible effects of a changing climate.

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Stanley A. Changnon Jr.
,
Wayne M. Wendland
, and
John L. Vogel

Abstract

Through a computer-based system, weather data from Illinois are collected daily, checked, and summarized into various climatic products within hours after collection. This system was controlled for two years to demonstrate system feasibility, determine user interest and product desires, and plan for statewide urge. This study focuses on usage of system products. The private sector (agribusiness news media, and private industry) was the most frequent and persistent user group, suggesting user-pay as a possible approach for funding such a system. State and federal agencies, farmers, and extension agents also use the system but primarily during weather stress periods. The characteristics of usage should help in the design and selection of products in other emerging state and regional systems for dissemination of climate data and information. The usage patterns also indicate how climate conditions impact various private and public sectors in a humid continental climate.

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William C. Ackermann
,
Stanley A. Changnon Jr.
, and
Ray Jay Davis

The Illinois State Water Survey, a state water resources research agency, initiated efforts in 1971 to develop and secure a law for Illinois that would permit and regulate weather modification activities. Such legislation was deemed a prime requirement, not only for the proper execution of scientific experiments on weather modification in Illinois but for the general benefit of citizens of Illinois through encouragement to properly conducted activities and protection from improperly conducted weather modification operations. (It was our intention to develop a “model law” that reflected the best aspects of weather modification legislation and experience in other states, and which would serve as a model for future legislation in other states.) The efforts began in October 1971 and were completed in September 1973 with the signing of the Illinois Weather Modification Control Bill and its accompanying appropriation bill. This paper describes the type of law desired, the activities performed to secure the law, and the primary aspects of the enacted Illinois law.

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Floyd A. Huff
,
Stanley A. Changnon Jr.
,
Chin-Fei Hsu
, and
Robert W. Scott

Abstract

As part of research concerned with operational seeding and evaluation techniques, analyses were made of two warm-season seeding projects involving rainfall enhancement: a 5-year (1975–79) aircraft seeding program conducted in 15 southwestern Kansas counties, and a ground generator seeding project conducted in 3 counties of northwestern Oklahoma in 1972–76. Data for 153 and 111 seeding days in Kansas and Oklahoma, respectively, were used. Rainfall data were obtained from the climatic raingage network of the National Weather Service. Seeding-day data were gratified according to meteorological parameters, including synoptic storm type, storm motion, and plume movement derived from the low-level wind field. Comparisons of 24-hour rainfall amounts in target and control areas were made. Movable controls determined from storm motions obtained from hourly radar data and upper-level winds were used to minimize control contamination by the seeding agent. In the southwestern Kansas operation, results indicated a target increase of 9% in the warm season rainfall, but this modest increase does not provide firm support for seeding enhancement considering rainfall natural variability, rainfall sampling deficiences, and other sources of sampling error. In the Oklahoma project, no substantial support was established for seeding-induced rainfall from the ground generator operations.

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Steven T. Sonka
,
Peter J. Lamb
,
Stanley A. Changnon Jr.
, and
Aree Wiboonpongse

Abstract

A three-step process is proposed to be most efficient for generating skillful climate forecasts which could reduce the adverse socioeconomic effects of climatic variability. These steps involve identifying weather-sensitive economic sectors, documenting the flexibility of these sectors with respect to likely forecast information, and the development of accordingly focused forecast capabilities. An illustration of the types of information needed to identify sector flexibility is provided for Midwest crop production. Finally, a pilot study using actual farmer data for east central Illinois suggests that increased corn yields could have resulted if producers had been forewarned of the benign weather conditions experienced during the 1979 growing season. This implies that skillful, properly structured climate forecasts may be useful to Midwest crop producers.

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Stanley A. Changnon
,
Griffith M. Morgan Jr.
,
Gary L. Achtemeier
,
Neil G. Towery
, and
Ronald C. Grosh

Abstract

A description is given of a broad program to Design and Experiment to Suppress Hail (DESH) in Illinois. This program draws on results acquired during 17 years of extensive hail research in Illinois. There are two principal tasks to DESH: the determination of the desirability and the feasibility of hail suppression experimentation in Illinois and the Midwest. Socio-economic studies have led to an affirmative conclusion on the desirability issues. The feasibility decision appears affirmative and rests on certain key results. Airborne cloud base seeding in the humid midwestern environment is possible but will be more difficult and expensive than in less humid areas. Radar will be needed for short-term forecasting, aircraft operations, identification of potential hailstorms, and in the evaluation of seeding effectiveness. Weather forecasting by objective techniques will be valuable in both operations and evaluation, and adequate objective techniques have been largely developed. The overall shape of the proposed experiment is now clear. It will consist of an impact monitoring effort, which will make assessments of societal, environmental and economic impacts and communicate with the public; an operational effort to execute the experiment according to the final detailed design; and an evaluation effort combining a variety of surface, synoptic and radar data to assess the efficacy of the chosen seeding technique.

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Stanley A. Changnon Jr.
,
Howard J. Critchfield
,
Robert W. Durrenberger
,
Charles L. Hosler
, and
Thomas B. McKee

The value of climate data and the information derived from the data still seems to be an unknown to many. Five persons engaged in providing climate services in different U.S. climatic zones have assembled a few widely different examples of recent uses of climate data and information. These help demonstrate the diversity of applications, and the value of the data and of those who can interpret them.

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Gerald A. Meehl
,
Thomas Karl
,
David R. Easterling
,
Stanley Changnon
,
Roger Pielke Jr.
,
David Changnon
,
Jenni Evans
,
Pavel Ya. Groisman
,
Thomas R. Knutson
,
Kenneth E. Kunkel
,
Linda O. Mearns
,
Camille Parmesan
,
Roger Pulwarty
,
Terry Root
,
Richard T. Sylves
,
Peter Whetton
, and
Francis Zwiers

Weather and climatic extremes can have serious and damaging effects on human society and infrastructure as well as on ecosystems and wildlife. Thus, they are usually the main focus of attention of the news media in reports on climate. There are some indications from observations concerning how climatic extremes may have changed in the past. Climate models show how they could change in the future either due to natural climate fluctuations or under conditions of greenhouse gas-induced warming. These observed and modeled changes relate directly to the understanding of socioeconomic and ecological impacts related to extremes.

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