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Earl S. Merritt

Abstract

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Earl S. Merritt

Abstract

Analyses of tropical perturbations in the Atlantic Region (commonly referred to as easterly waves), utilizing observations from meteorological satellites, reveal that five distinctly different cloud distributions occur. These patterns are both linear (similar to the classic Riehl model of the easterly wave) and vortical. The vortical patterns appear roost frequently and are often related to a closed cyclonic circulation in the mid-troposphere.

Calculations of the horizontal and vertical distributions of divergence and vorticity indicative of the mid-tropospheric circulation in an intense disturbance are shown.

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EARL S. MERRITT and RAYMOND WEXLER

Abstract

An analysis is made of the generation, advection, and dissipation processes of the cirrus canopy in tropical storms with particular emphasis on the formation of sharp edges. Although subsidence and accompanying evaporation may be factors, this formation is closely tied with the wind flow pattern near the edges. The stronger the radial wind velocity in the vicinity of the edges, the greater is the rate of subsidence required to evaporate the cloud over a distance sufficiently short so that the edge may be considered sharp.

Analyses of the wind fields in typical hurricanes indicate that cirrus generated at the eye wall and advected outward could produce in 12 to 18 hr. a canopy similar to those observed by meteorological satellites. If, in addition, generation occurs in the spiral arms, these times are shortened somewhat. Sharp edges would occur in regions where the radial outflow becomes small, probably less than 1 m. sec.−1, and where the tangential velocity is at a relative maximum.

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Kevin P. McNew, Harry P. Mapp, Claude E. Duchon, and Earl S. Merritt

Numerous studies have examined the importance of weather information to farmers and ranchers across the U.S. This study is focused on the kinds of weather information received by farmers and ranchers, the sources of that information, and its use in production and marketing decisions. Our results are based on a survey of 292 producers from the principal agricultural areas of Oklahoma. Producers were classified into five categories related to their source of income from crop and livestock sales.

Among temperature, precipitation, relative humidity, and wind speed, temperature information was most widely received. Forecast lengths of highest interest were 24-h and 5-day forecasts. Precipitation information was used by many respondents for planting and harvesting decisions. Weather data and forecasts seem to be of greater value to diversified crop and livestock operators than specialized crop and livestock, perhaps due to more frequent timing decisions. Relative humidity and wind information appear to be important especially during specific times of the growing season, for example, at harvest time and time of pesticide application. Television is the primary source of weather information for more than 60% of the producers.

It appears that there may be a role for both public and private entities in transforming weather data and forecasts into recommendations to crop and livestock producers. Further research is needed to determine the potential value of weather information for alternative production, marketing and livestock decisions, different categories of producers, and different geographic regions.

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