Resumen
In urban areas high air pollutant concentrations may be observed, mostly within street canyons, where buildings and other obstacles disturb the airflow and turbulence. Air motions inside the street canyons are influenced by aerodynamic and thermal effects and by the movements of the vehicles. In this article, we analyze hourly CO and NOx concentrations measured at 1.5 m height on the west side of a street canyon of Göttinger Strasse in Hannover (Germany) and background CO and NOx, wind speed and direction that have been measured on the roof of a nearby building. Information of traffic flow in the street is also available. Results show the presence of a vortex cell inside the street canyon when the ambient wind is greater than 1.8 m/s and is mainly perpendicular to the street axis. We evaluated of the relative influence of ambient and traffic-induced turbulences on local concentrations inside the canyon. The results show that traffic-induced turbulence becomes important when the wind is lower than 2 m/s.