Evaluation of two street canyon air quality models using data from European cities

Abstract

This paper presents a sensitivity analysis of the Operational Street Pollution Model (OSPM) and an evaluation of OSPM and the Assessing the Environment Of Locations In Urban Streets (AEOLTUS) model. Both models calculate airborne concentrations of exhaust gases emitted by motor vehicles within street canyons. They perform best when the street canyon aspect ratio is 1.0. OSPM and AEOLIUS have been evaluated using data collected over a two-year period (1 994- 95) in Jagtvej, Copenhagen, Denmark. Further evaluation of the models was carried out using data collected in Giittinger Strasse, Hannover (1994) and Schildhom Strasse, Berlin (1995), both in Germany. In all cases, model runs were carried out for carbon monoxide (CO). In the case of OSPM, two sets of newly proposed emission factors were used for the street canyons in Germany. In the calculation of these factors, the urban driving patterns and variations in the composition of the vehicle fleet according to the engine capacity were assumed as the most appropriate for the cases considered. Furthermore, parameters such as engine operating temperature and the use of catalytic converter were taken into account. Scatter plots of modelled against measured CO concentration yielded an average regression coefficient of 0.90 for the street canyons considered. With the newly proposed emission factors for Germany a lower regression coefficient was obtained. From similar scatter plots, the AEOLIUS model gave a regression coefficient of 0.86 for Jagtvej in 1994 and 0.78 for 1995. For Gottinger and Schildhorn Strasse, the regression coefficient obtained was 0.8 1.