Winter Urban Chemistry and Denver’s Brown Cloud: Part 1—Light Extinction and Visibility

Autor: Steven L. Heisler, G. M. Hidy, G. T. Wolff, John G. Watson
Rok vydání: 2020
Předmět:
Zdroj: Aerosol Science and Engineering. 4:64-79
ISSN: 2510-3768
2510-375X
DOI: 10.1007/s41810-020-00055-5
Popis: An example of winter visibility impairment from air pollution has been observed over Denver, Colorado (USA) from studies of the sources and characteristics of the haze conducted since the 1960s. A 1978 keystone study of this phenomenon provides the basis for many subsequent experimental designs. The 1978 results show how the coupling of short duration measurements of meteorological processes and air chemistry, combined with source data, yield key information about urban haze. The study employed six stations, with measurements including diurnal particle concentrations and optical properties. The results affirmed the association between the mass concentration of fine particles and light extinction. Extinction in the haze depended mainly on particles containing carbon, sulfate, and nitrate, with contributions from dust and NO2 absorption. Diurnal data show the spatio-temporal variability of mass concentration and light extinction across the city, which are related to sources and meteorology. The composition of fine particles is used with receptor modeling for source apportionment of extinction. Results from this and later studies are relevant to current conditions not only in Denver, but also cities across North America and Asia, and demonstrate that “newly discovered” relationships between visibility and particulate matter were evident more than 4 decades ago.
Databáze: OpenAIRE
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