Some features of the ozone climatology of Ontario, Canada and possible contributions of stratospheric ozone to surface concentrations

摘要: Background ozone concentration displayed distinct seasonal variations at all stations, with a maximum of about 40 ppb in spring and minimum 23 autumn. The monthly yearly mean diurnal urban stations exhibited bi-modal characteristics not evident rural sites. Two daily maxima minima were recorded but only one second minimu min the evening was shown to be related high levels nitric oxide, while nighttime heat island considered main cause maximum. One-day resultant trajectories show that most frequent highest concentrations associated relatively light moderate south southwesterly flow or strong winds. Although there several recognizable meteorological regimes elevated over Ontario, those weak pressure gradients favourable for onset lake breeze flows on west side slow-moving centres crossing eastern United States resulted concentrations. Ozone Ontario may mostly attributed long distance transport emissions from major industrial areas border. However, tropospheric stratospheric contributions cannot ruled out even source times. A case study possible influx into troposphere is presented.