Atmospheric and Climate Science Directorate

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Providing Air Quality Forecasts and Advisories for Canadians

The (CHRONOS) Chemical Transport Model

One of the challenges of any research program is the transfer of knowledge and technology from a research environment to an operational environment where the investment in research and development is paid back through improved products and services to the public. The challenge is even greater when the final product must be delivered in real-time, in a collaborative manner, and involving multiple levels of government.

Air quality forecasts and advisories are important and complement the Air Quality Index Program. A few thousand premature deaths are attributed to air pollution in Canada each year. Anyone with respiratory or cardiovascular conditions can benefit from taking special precautions during an air quality advisory, issued when pollution levels are expected to be high. Others can make informed decisions on a range of actions that either reduce their exposure or contribute to reducing air pollution emissions.

At the centre of the Meteorological Service of Canada's MSC capability to produce and support air quality forecasts and advisories is a state-of-the-art computer model – (CHRONOS) (Canadian Hemispheric and Regional Ozone and NOX System). It is a comprehensive air quality model containing a full description of atmospheric chemistry and meteorological processes. (CHRONOS) uses a North American emission inventory for atmospheric chemistry, and MSC's weather forecast model for transport processes.

The development of (CHRONOS) started in the early 1990s and it has emerged as MSC's model of choice for smog-related forecasts. It has recently made the transition from a research environment into operations. These model outputs feed into air quality forecasts and advisories. The national smog forecasting program builds on and complements existing regional, provincial and municipal capabilities and measurements to deliver air quality forecasts and advisories.

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The distribution of ground-level ozone for June 8, 2003 across North America as forecast by the (CHRONOS) model.The daily forecasts can be viewed on-line at http://www.msc-smc.ec.gc.ca/aq_smog

(CHRONOS) can also be used to answer questions in support of policy development such as, “How much will air quality improve with the implementation of a given set of management actions or control strategies to reduce air pollution emissions?”. This provides valuable insights for air quality policy makers, notably in support of the development and implementation of Canada-Wide Standards for Particulate Matter and Ozone. Canada-U.S. negotiations over crossborder transport of smog and related pollutants have also benefited from insights provided by (CHRONOS).

The use of (CHRONOS) is a good example of bringing a research model into an operational environment and using it as a tool to support air quality forecast services to Canadians. It's an excellent example of research making a difference.

These images show the contrast between a clean air day and a ‘smog' day in downtown Toronto, Ontario.

“A few thousand people die prematurely each year in Canada due to poor air quality. High quality and accurate air quality forecasts are essential to helping protect the health of Canadians. MSC's (CHRONOS) model assists regional, provincial and municipal agencies to deliver air quality advisories, which in turn enable Canadians to take action to protect themselves from poor air quality.”
Dr. Quentin Chiotti
Air Programme Director Pollution Probe

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