Ozone in the troposphere: Measurements, climatology, budget, and trends

Abstract An improved understanding of the global tropospheric ozone budget has recently become of great interest, both in Canada and elsewhere. Improvements in both modelling and measurement have made it possible for weather centres to begin to forecast air quality using numerical weather prediction models. Despite substantial progress, there are many open questions regarding tropospheric ozone photochemistry, long‐range transport and the importance of the stratospheric source; this remains an area of very active research. Since ozone in association with particulate matter causes respiratory problems in humans, trends and forecasting of future surface ozone levels are also of great importance. The current status of measurement and modelling, as well as the current understanding of tropospheric ozone budgets and trends, are reviewed, with an emphasis on Canada within the global context.