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DOI: 10.1191/0309133305pp442ra A review of turbulence in the very stable nocturnal boundary layer and its implications for air qualityDivision of Environmental Health and Risk Management, Department of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK, j.salmond{at}bham.ac.uk
Department of Geography, University of British Columbia, 1984 West Mall, Vancouver, B.C., V6T 1Z2, Canada Turbulence in the very stable nocturnal boundary layer is weak and typically characterized by intermittent bursts of activity. It often exists in isolated layers or pockets generated primarily from localized shear instabilities. As a result, turbulence is rarely in equilibrium with the conditions of the underlying surface. Given the layered structure of the nocturnal boundary layer, the spatial and temporal characteristics of turbulent activity (and resulting vertical mixing) can have a significant affect on local air quality at hourly to diurnal scales. However, while there is a wealth of information concerning turbulent processes operating during daytime conditions, until recently comparatively few studies have focused on the nocturnal case. Nevertheless the three-dimensional distribution of pollutants in the nocturnal boundary layer may have a significant impact on local pollutant budgets at a variety of temporal and spatial scales. This paper reviews recent progress in our understanding of the structure of, and processes operating in, the very stable nocturnal boundary layer. Then, drawing upon case studies from the Lower Fraser Valley, of British Columbia, Canada, it considers the implications of these developments for pollutant transport and surface air quality.
Key Words: complex terrain nocturnal boundary layer ozone turbulence
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