Current and Future Developments in Numerical Air Quality Forecasting in Canada

Environment Canada produces twice-daily, 48-h operational air quality (AQ) forecasts for a domain covering North America. At the core of the forecast system is the GEM-MACH model, an on-line coupled meteorology and chemistry model that includes a representation of gas-phase, aqueous-phase, and heterogeneous chemistry and a number of particulate matter (PM) processes. In this paper, a brief description of the recent changes to the Canadian National AQ Forecasting System is given, followed by a discussion of future development plans. The objective for the next version of the system is to deliver improved AQ forecasts by improving initial and boundary conditions and representations of emissions and processes.