Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4444682 | Atmospheric Environment | 2006 | 13 Pages |
Abstract
Pollution wind sector or rose analyses show that under South-Easterly winds, many areas of the UK experience an increase in mean airborne particulate matter concentration of up to 30%Â over the average for all directions. This is often attributed solely to long-range transport of pollutants from continental Europe. Here, we present a rose analysis that suggests an additional influence of boundary layer ventilation. The directional increase in pollutant concentration is found to coincide with a 45-55%Â reduction in ventilation, obtained from ECMWF reanalysis. The reduced ventilation will increase the concentration of locally emitted particulate matter. This effect is explained by low average South-Easterly wind speeds, and advection of high-level warm air from continental Europe, which stabilises the boundary layer, and reduces the boundary layer height. A similar dependence of ventilation on wind direction was found across most of the world, so that a similar effect on pollution roses may be present at most locations. The high number of particulate matter exceedance days for Easterly flow was not found to be associated with a high frequency of extremely low ventilation conditions, suggesting that ventilation alone cannot explain these events.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Atmospheric Science
Authors
Matthew Rigby, Roger Timmis, Ralf Toumi,