title: An open-terrain line source model coupled with street-canyon effects to forecast carbon monoxide at traffic roundabout.
abstract: A double-lane four-arm roundabout, where traffic movement is continuous in opposite directions and at different speeds, produces a zone responsible for recirculation of emissions within a road section creating canyon-type effect. In this zone, an effect of thermally induced turbulence together with vehicle wake dominates over wind driven turbulence causing pollutant emission to flow within, resulting into more or less equal amount of pollutants upwind and downwind particularly during low winds. Beyond this region, however, the effect of winds becomes stronger, causing downwind movement of pollutants. Pollutant dispersion caused by such phenomenon cannot be described accurately by open-terrain line source model alone. This is demonstrated by estimating one-minute average carbon monoxide concentration by coupling an open-terrain line source model with a street canyon model which captures the combine effect to describe the dispersion at non-signalized roundabout. The results of the modeling matched well with the measurements compared with the line source model alone and the prediction error reduced by about 50%. The study further demonstrated this with traffic emissions calculated by field and semi-empirical methods.
authors.affiliation: Center for the Environment, Indian Institute of Technology Guwahati, India.
authors.forename: Suresh
authors.initials: S
authors.lastname: Pandian
authors.forename: Sharad
authors.initials: S
authors.lastname: Gokhale
authors.forename: Aloke Kumar
authors.initials: AK
authors.lastname: Ghoshal
mesh_terms: D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D002248:Carbon Monoxide / Q000032:analysis*; D002947:Cities; D004784:Environmental Monitoring / Q000379:methods*; D008956:Models, Chemical; D014186:Transportation; D001335:Vehicle Emissions / Q000032:analysis
chemical_list: D000393:Air Pollutants; D001335:Vehicle Emissions; D002248:Carbon Monoxide