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- catalog abstract "The mixing-layer height and the average wind speed within the mixing layer were calculated twice for each day of a 5-year record of upper air observations at 62 National Weather Service stations int he contiguous United States. The times of day of these calculations are morning and mid-afternoon. A rough allowance was made for effects of the urban "heat island" on the morning mixing heights. The morning and afternoon times coincide approximately with those of maximum and secondary minimum concentrations of slow-reacting pollutants in cities. These calculations illustrate the typical large diurnal variation in atmospheric dispersion. Twenty charts present seasonal and annual, and morning and afternoon mean mixing heights and wind speeds. A model of some general dispersion features over urban areas is described in which the normalized pollutant concentration averaged over a city is a function of mixing height, wind speed, and city size (distance the wind travels across the city). Frequency values of mixing height by wind speed are used with the model to calculate average normalized concentration frequencies for each weather station. Thirty charts present isopleth analyses of seasonal and annual, and morning and afternoon normalized pollutant concentrations that were exceeded 10, 25, and 50 percent of the time for specified city sizes. The occurrence of episodes during which upper limits on mixing height and wind speed were not exceeded were determined from the daily morning and afternoon values of these parameters. Isopleths of the total number of episode-days for episodes lasting at least 2 days and at least 5 days with various limiting mixing-height and wind-speed values are presented in 20 charts.".
- catalog contributor b4445565.
- catalog contributor b4445566.
- catalog created "1972.".
- catalog date "1972".
- catalog date "1972.".
- catalog dateCopyrighted "1972.".
- catalog description "Bibliography: p. 117-118.".
- catalog description "The mixing-layer height and the average wind speed within the mixing layer were calculated twice for each day of a 5-year record of upper air observations at 62 National Weather Service stations int he contiguous United States. The times of day of these calculations are morning and mid-afternoon. A rough allowance was made for effects of the urban "heat island" on the morning mixing heights. The morning and afternoon times coincide approximately with those of maximum and secondary minimum concentrations of slow-reacting pollutants in cities. These calculations illustrate the typical large diurnal variation in atmospheric dispersion. Twenty charts present seasonal and annual, and morning and afternoon mean mixing heights and wind speeds. A model of some general dispersion features over urban areas is described in which the normalized pollutant concentration averaged over a city is a function of mixing height, wind speed, and city size (distance the wind travels across the city). Frequency values of mixing height by wind speed are used with the model to calculate average normalized concentration frequencies for each weather station. Thirty charts present isopleth analyses of seasonal and annual, and morning and afternoon normalized pollutant concentrations that were exceeded 10, 25, and 50 percent of the time for specified city sizes. The occurrence of episodes during which upper limits on mixing height and wind speed were not exceeded were determined from the daily morning and afternoon values of these parameters. Isopleths of the total number of episode-days for episodes lasting at least 2 days and at least 5 days with various limiting mixing-height and wind-speed values are presented in 20 charts.".
- catalog extent "xi, 118 p.".
- catalog isPartOf "Office of Air Programs publication no. AP-101".
- catalog isPartOf "United States. Environmental Protection Agency. Office of Air Programs. Publication ; no. AP-101.".
- catalog issued "1972".
- catalog issued "1972.".
- catalog language "eng".
- catalog publisher "Research Triangle Park, N. C., Environmental Protection Agency, Office of Air Programs; [for sale by the Supt. of Doc., U. S. Govt. Print. Off., Washington]".
- catalog spatial "United States.".
- catalog subject "628.5/3/0155515180973".
- catalog subject "Air Pollution United States.".
- catalog subject "Boundary layer (Meteorology)".
- catalog subject "Models, Theoretical United States.".
- catalog subject "Models, Theoretical".
- catalog subject "QC983 .H64".
- catalog subject "Synoptic climatology United States.".
- catalog subject "Urban climatology United States.".
- catalog subject "W1 OF454K no.101 1972".
- catalog subject "Weather United States.".
- catalog subject "Weather forecasting United States.".
- catalog subject "Weather".
- catalog title "Mixing heights, wind speeds, and potential for urban air pollution throughout the contiguous United States [by] George C. Holzworth.".
- catalog type "text".