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Wes P. Kent and Scott C. Sheridan

Abstract

Although it is often suggested that direct sunlight may affect a player’s vision, no published studies have analyzed this interaction. In this research, a variety of statistical tests were utilized to study how baseball variables respond to different cloud cover conditions. Data from more than 35 000 Major League Baseball games, spanning the seasons from 1987 through 2002, were studied. Eleven baseball variables covering batting, pitching, and fielding performance were included. Overall responses were analyzed, as well as individual responses at 21 different stadiums. Home and away team performances were evaluated separately. This study then synthesized the synergistic differences in offensive production, pitching performance, and fielding performance into changes in the “home field advantage.”

Offensive production generally declines during clearer-sky daytime games compared to cloudy-sky daytime games, while pitching performance increases as conditions become clearer. Strikeouts show the strongest response in the study, increasing from 5.95 per game during cloudy-sky conditions to 6.40 per game during clear-sky conditions. The number of errors per game increases during clear-sky daytime games compared to cloudy-sky daytime games, while fly outs increase and ground outs decrease between daytime and nighttime games, regardless of the amount of cloud cover. Results at individual stadiums vary, with some stadiums displaying a very strong association between baseball performance and changes in cloud cover, while others display a weak association. All of these impacts affect the home field advantage, with the home team winning 56% of the games played under clear skies compared to 52.3% of the games played under cloudy skies.

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Scott C. Sheridan, P. Grady Dixon, Adam J. Kalkstein, and Michael J. Allen

Abstract

Much research has shown a general decrease in the negative health response to extreme heat events in recent decades. With a society that is growing older, and a climate that is warming, whether this trend can continue is an open question. Using eight additional years of mortality data, we extend our previous research to explore trends in heat-related mortality across the United States. For the period 1975–2018, we examined the mortality associated with extreme-heat-event days across the 107 largest metropolitan areas. Mortality response was assessed over a cumulative 10-day lag period following events that were defined using thresholds of the excess heat factor, using a distributed-lag nonlinear model. We analyzed total mortality and subsets of age and sex. Our results show that in the past decade there is heterogeneity in the trends of heat-related human mortality. The decrease in heat vulnerability continues among those 65 and older across most of the country, which may be associated with improved messaging and increased awareness. These decreases are offset in many locations by an increase in mortality among men 45–64 (+1.3 deaths per year), particularly across parts of the southern and southwestern United States. As heat-warning messaging broadly identifies the elderly as the most vulnerable group, the results here suggest that differences in risk perception may play a role. Further, an increase in the number of heat events over the past decade across the United States may have contributed to the end of a decades-long downward trend in the estimated number of heat-related fatalities.

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J. D. Price, S. Vosper, A. Brown, A. Ross, P. Clark, F. Davies, V. Horlacher, B. Claxton, J. R. McGregor, J. S. Hoare, B. Jemmett-Smith, and P. Sheridan

During stable nighttime periods, large variations in temperature and visibility often occur over short distances in regions of only moderate topography. These are of great practical significance and yet pose major forecasting challenges because of a lack of detailed understanding of the processes involved and because crucial topographic variations are often not resolved in current forecast models. This paper describes a field and numerical modeling campaign, Cold-Air Pooling Experiment (COLPEX), which addresses many of the issues.

The observational campaign was run for 15 months in Shropshire, United Kingdom, in a region of small hills and valleys with typical ridge–valley heights of 75–150 m and valley widths of 1–3 km. The instrumentation consisted of three sites with instrumented flux towers, a Doppler lidar, and a network of 30 simpler meteorological stations. Further instrumentation was deployed during intensive observation periods including radiosonde launches from two sites, a cloud droplet probe, aerosol monitoring equipment, and an instrumented car. Some initial results from the observations are presented illustrating the range of conditions encountered.

The modeling phase of COLPEX includes use of the Met Office Unified Model at 100-m resolution, and some brief results for a simulation of an intensive observation period are presented showing the model capturing a cold-pool event. As well as aiding interpretation of the observations, results from this study are expected to inform the design of future generations of operational forecasting systems

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J. Heintzenberg, A. Wiedensohler, T. M. Tuch, D. S. Covert, P. Sheridan, J. A. Ogren, J. Gras, R. Nessler, C. Kleefeld, N. Kalivitis, V. Aaltonen, R-T. Wilhelm, and M. Havlicek

Abstract

This study determined measured and Mie-calculated angular signal truncations for total and backscatter TSI, Inc., nephelometers, as a function of wavelength and for particles of known size and composition. Except for the total scattering channels, similar agreements as in a previous study of measured and calculated truncations were derived for submicrometer test aerosols. For the first time, instrument responses were also determined for supermicrometer test aerosols up to 1.9 μm in geometric mean diameter. These supermicrometer data confirm the theoretical predictions of strong angular truncations of the total scatter signals in integrating nephelometers due to the limited range of measured forward scattering angles. Truncations up to 60% were determined for the largest measured particles. Rough empirical truncation corrections have been derived from the calibration data for Radiance Research and Ecotech nephelometers for which no detailed response characteristics exist. Intercomparisons of the nephelometers measuring urban atmospheric aerosols yield average deviations of the slope from a 1:1 relation with a TSI reference nephelometer of less than 7%. Average intercepts range between +0.53 and −0.19 Mm−1. For the Radiance Research and Ecotech nephelometers ambient regressions of the Radiance Research and Ecotech instruments with the TSI nephelometer show larger negative intercepts, which are attributed to their less well characterized optics.

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Elisabeth Andrews, Patrick J. Sheridan, John A. Ogren, Derek Hageman, Anne Jefferson, Jim Wendell, Andrés Alástuey, Lucas Alados-Arboledas, Michael Bergin, Marina Ealo, A. Gannet Hallar, András Hoffer, Ivo Kalapov, Melita Keywood, Jeongeun Kim, Sang-Woo Kim, Felicia Kolonjari, Casper Labuschagne, Neng-Huei Lin, AnneMarie Macdonald, Olga L. Mayol-Bracero, Ian B. McCubbin, Marco Pandolfi, Fabienne Reisen, Sangeeta Sharma, James P. Sherman, Mar Sorribas, and Junying Sun

Abstract

To estimate global aerosol radiative forcing, measurements of aerosol optical properties are made by the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL)’s Global Monitoring Division (GMD) and their collaborators at 30 monitoring locations around the world. Many of the sites are located in regions influenced by specific aerosol types (Asian and Saharan desert dust, Asian pollution, biomass burning, etc.). This network of monitoring stations is a shared endeavor of NOAA and many collaborating organizations, including the World Meteorological Organization (WMO)’s Global Atmosphere Watch (GAW) program, the U.S. Department of Energy (DOE), several U.S. and foreign universities, and foreign science organizations. The result is a long-term cooperative program making atmospheric measurements that are directly comparable with those from all the other network stations and with shared data access. The protocols and software developed to support the program facilitate participation in GAW’s atmospheric observation strategy, and the sites in the NOAA/ESRL network make up a substantial subset of the GAW aerosol observations. This paper describes the history of the NOAA/ESRL Federated Aerosol Network, details about measurements and operations, and some recent findings from the network measurements.

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