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Community Multiscale Air Quality Modeling System (CMAQ)

Overview of Science Processes in CMAQ

Overview of Science Processes in CMAQ

CMAQ is a first-principles scientific computer model that comprehensively represents the most important processes affecting air quality and atmospheric chemistry. Emissions from a wide range of sources are included, as well as transport by winds and deposition due to precipitation events. CMAQ uses an extensive database of atmospheric chemical reactions to predict the chemical production and loss of hundreds of pollutants as they are carried downwind from their sources. In addition to gas-phase species, many pollutants exist partially or wholly in airborne particles, giving them the potential to interact with incoming solar radiation and clouds in complicated ways. 

A major challenge for models like CMAQ is capturing the variability in human-driven emissions and weather patterns across the U.S. or around the globe. In addition to variations in space, CMAQ methods have to deal with emission and weather changes that happen over decades, throughout the seasons, and even over the course of a day. Even with these challenges, it’s important for CMAQ to represent the atmosphere and all its complexities accurately, since gases and particles included in the model can have major impacts on public health and the environment.