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David Changnon and Stanley A. Changnon

Abstract

Uses of climate information have grown considerably in the past 15 years as a wide variety of weather-sensitive businesses sought to deal effectively with their financial losses and manage risks associated with various weather and climate conditions. Availability of both long-term quality climate data and new technologies has facilitated development of climate-related products by private-sector atmospheric scientists and decision makers. Weather derivatives, now widely used in the energy sector, allow companies to select a financially critical seasonal weather threshold, and, for a price paid to a provider, to obtain financial reparation if this threshold is exceeded. Another new product primarily used by the insurance industry is weather-risk models, which define the potential risks of severe-weather losses across a region where few historical insured loss data exist. Firms develop weather-risk models based on historical storm information combined with a target region’s societal, economic, and physical conditions. Examples of the derivatives and weather-risk models and their uses are presented. Atmospheric scientists who want to participate in the development and use of these new risk-management products will need to broaden their educational experience and develop knowledge and skills in fields such as finance, geography, economics, statistics, and information technology.

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Stanley A. Changnon and David Changnon

Abstract

Hail-day occurrences during a 100-yr period, 1896–1995, derived from carefully screened records of 66 first-order stations distributed across the United States, were assessed for temporal fluctuations and trends. Shorter-term (5- and 10-yr) fluctuations varied greatly and were often dissimilar between adjacent stations reflecting localized differences in hailstorm activity, making temporal interpretations difficult. But temporal fluctuations based on 20-yr and longer periods exhibited regional coherence reflecting the control of large-scale synoptic hail-producing systems on the point distributions over broader areas. Classification of station fluctuations based on 20-yr periods revealed five types of distributions existed across most of the nation. One present in the Midwest had a peak in hail activity in 1916–35 followed by a general decline to 1976–95. Another distribution had a midcentury peak and was found at stations in three areas: the central high plains, northern Rockies, and East Coast. The third distribution peaked during 1956–75 and was found at stations in the northern and south-central high plains. The fourth temporal distribution showed a steady increase during the 100-yr period, peaking in 1976–95, and was found in an area from the Pacific Northwest to the central Rockies and southern plains. The fifth distribution found at stations in the eastern Gulf Coast had a maximum at the beginning of the century and declined thereafter. The 100-yr linear trends defined four regions across the United States with significant up trends in the high plains, central Rockies, and southeast, but with decreasing trends elsewhere in the nation. These up trends have occurred in areas where hail damage is greatest, and the trends matched well with those defined by crop-hail insurance losses and those found in studies of thunderstorm trends. The national average based on all station hail values formed a bell-shaped 100-yr distribution with hail occurrences peaking in midcentury. Thunderstorm data from the 66 stations, also based on screening to ensure quality data, revealed a bell-shaped distribution similar to the hail-day distribution, and national hail insurance loss values have declined since the 1950s, also agreeing with the hail-day decrease since midcentury. The national distribution differs markedly from certain regional distributions illustrating the importance of using regional analysis to assess temporal fluctuations in severe weather conditions.

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David Changnon and Stanley A. Changnon

Abstract

Crop-hail insurance loss data for 1948–94 are useful as measures of the historical variability of damaging hail in those 26 states where most crop damages occur. However, longer records are needed for various scientific and business applications, as well as information on potential losses in United States’ areas without crop insurance. The long-term (1901 to present) data on hail-day incidences, as derived from National Weather Service historical station records, were investigated to determine if some form of a hail-day expression related well to the insurance losses. The areal extent of insured areas of Illinois, Texas, and Nebraska experiencing growing season frequencies of hail days matching or exceeding the once in 10-yr frequencies was found to have the best relationship with insured loss values. The computed correlation coefficients were +0.97 for Illinois, +0.73 for Texas, and +0.91 for Nebraska. These values appear to be a useful surrogate for 1) estimating pre-1948 loss values, 2) estimating loss values in areas with no insurance, and 3) further research involving other states with different crop and hail conditions.

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Stanley A. Changnon Jr.

Abstract

Historical (1901–85) summer (June–August) rainfall data in central Illinois were used to construct three typical rain conditions: one representing the typical dry summer (based on the driest 20% of the summers of the past 85 years), a typical wet summer (from the 20% wettest), and the near-average summer rainfall conditions (the 20% nearest the long-term average). Monthly rain totals for each type were established first, then daily rain frequencies were used to define all individual rain day amounts, and historical rain-day amounts by date were used to assign rain days to dates throughout the three types of summers. In-day conditions relating to rainfall rates, time of rain, and durations were constructed for each day of rain. The resulting three summer rainfall conditions are being used to guide applications of water onto agricultural test plots (protected from natural rains) to measure crop yield effects from weather modification but the approach and system could serve other applications like effects of climate change.

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Stanley A. Changnon Jr.
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Stanley A. Changnon Jr.

A midwestern group of 46 scientists and 16 nonscientists were polled at a recent AMS meeting about their beliefs on climate change, the CO2 issue, and the overall importance of these issues. Most indicated a belief in a trend to a climate that is colder, wetter, and has more weather variability. The group also indicated that the reports on CO2 were confusing to them and especially to the public. Finally, they indicated that the ongoing climate shift has been important to their lives.

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Stanley A. Changnon Jr.

Abstract

The distribution of hail days during 1961–80 in the northern Great Plains-Midwest was evaluated on a temporal and spatial basis to help interpret crop-hail losses. Comparisons with earlier (1901–60) hail day data revealed the seven-state study area contained eight permanent areas of high and low incidences found in any 5-year or longer period. The high hail incidence areas were related either to major topographic features or to areas of frequent frontal occurrences. Certain other areas of high or low hail incidence appeared at random locales, lasted 5 to 20 years, and disappeared. The annual and July incidences of hail increased sporadically but steadily from 1901 to 1980 in the Dakotas, Nebraska and Minnesota, reaching a peak during 1961–80. This has led to relatively more crop damage in recent years. In Montana, eastern Iowa, and Illinois, hail has decreased to a low in 1961–80. During the 1961–80 period, hail maximized in 1961–65, being 30% more frequent than in any subsequent 5-year period.

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Stanley A. Changnon Jr.

Mesoscale networks are designed and used to serve various specific purposes. Experience in the operation of several meso-networks has been used to describe those factors to be considered in their design, installation, and operations. Successful operation of networks depends on good management that can optimize project goals and available resources. The primary factors involved include network planning, procurement of facilities and staff, instrument siting, data collection, maintenance, calibration, data processing, and the eventual data bank. Long-term data retention is useful since network data frequently get re-used in subsequent, unforseen research. METROMEX, an on-going program studying urban effects on weather, has 15 sub-networks, and their designs and operations are used as illustrations. Public relations, unexpected problems, and data processing are high-lighted for the rainfall and severe storm networks.

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Stanley A. Changnon Jr.

Abstract

An understanding of applied climatology and its information-generating research requires recognition of the total cause-and-effect spectrum including the issue detection, the research effort pursued, the type of product, the users, and their applications of findings. Twenty climatic information studies done at the Illinois Climate Center in 1977-79 are reviewed to illustrate why they were done, often as a result of general inquiries or specific requests, and a few of their key results. The studies each required from weeks to months to complete. Most users of the results fell in two general classes, government or business-industry. The studies revealed applications in three areas: the design of facilities, the planning and/or operations of facilities and activities, and the climatic assessment of weather extremes.

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Stanley A. Changnon Jr.

Abstract

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