Temperature Inversion Breakup with Impacts on Air Quality in Urban Valleys Influenced by Topographic Shading

• Published in: Journal of applied meteorology and climatology Vol. 54; no. 2; pp. 302 - 321
• Main Authors: Rendón, Angela M., Salazar, Juan F., Palacio, Carlos A., Wirth, Volkmar
• Format: Journal Article
• Language: English
• Published: Boston American Meteorological Society 01-02-2015
• Subjects: Air pollution; Air quality; Air temperature; Breakup; Circulation; Emission analysis; Experiments; Influence; Inversion layers; Low temperature; Meteorology; Meteors; Outdoor air quality; Pollutants; Pollution dispersion; Pollution transport; Radiation; Shading; Simulation; Sloping terrain; Smog; Studies; Sun; Temperature; Temperature effects; Temperature inversion; Temperature inversions; Topographic effects; Topography; Transport; Turbulence; Urban air quality; Urban areas; Urban heat islands; Valleys; Ventilation; Wind; Winds
• ISSN: 1558-8424; 1558-8432
• DOI: 10.1175/JAMC-D-14-0111.1

Urban valleys can experience serious air pollution problems as a combined result of their limited ventilation and the high emission of pollutants from the urban areas. Idealized simulations were analyzed to elucidate the breakup of an inversion layer in urban valleys subject to a strong low-level temperature inversion and topographic effects on surface heating such as topographic shading, as well as the associated air pollution transport mechanisms. The results indicate that the presence and evolution in time of the inversion layer and its interplay with an urban heat island within the valley strongly influence the venting of pollutants out of urban valleys. Three mechanisms of air pollution transport were identified. These are transport by upslope winds, transport by an urban heat island–induced circulation, and transport within a closed slope-flow circulation below an inversion layer.