MODELING OF OZONE FORMATION AT A RURAL SITE IN SOUTHERN ONTARIO

A one-dimensional time-dependent photochemical diffusion model has bee n used to simulate the chemical and vertical transport processes occur ring at a rural location within Southern Ontario. The model output has been compared with the extensive measurements of several atmospheric trace gases which were made at a rural site in Southern Ontario as par t of SONTOS (Southern Ontario Oxidant Study) during the summer of 1999 In particular, the measurements include various VOCs, odd nitrogen co mponents and RO(x) which have been explicitly included in the model. F or the case examined, observations at the site are typical of unpollut ed background conditions and the model is able to reproduce the observ ed variation of many of the key trace gas species observed. Though the site is remote from large population centers there appear to be impor tant local emissions of NOx and non-methane hydrocarbons (NMHC). Model ling results suggest that For the day studied approximately 10 ppb of ozone was photochemically produced, and that the production of ozone w as limited by the availability of NOx (NO + NO2). At the observed leve ls isoprene does not play a major role in the production of ozone. A c omparison of observations and model calculations for peroxy radical an d HNO3 concentrations indicate a disagreement between the model and me asurements. Copyright (C) 1996 Elsevier Science Ltd