National Air Quality Forecast Capability Predictions: Chemistry, Meteorology and Emission Impacts

NOAA provides operational ozone predictions and testing of fine particulate matter (PM2.5) predictions over the United States (U.S.). These predictions are produced by the system that combines meteorological predictions from the North American Mesoscale (NAM) model and chemical processes within the Community Multiscale Air Quality (CMAQ) model. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model driven by NAM is used to provide operational wildfire smoke and dust storm predictions. Ozone, smoke and dust predictions are available at http://airquality.weather.gov/.

We will present impacts of upgrades to representations of chemistry, meteorology and emissions in NOAA's air quality predictions. An upgrade to CMAQ model to use a newer representation of chemical processes was implemented in the last year. Meteorological model upgrades occur routinely. Over the several recent years emission sources have been updated using emission projections, by including data from a more recent emissions inventory, and by including emissions from intermittent wildfire and dust storm sources.

Due to these updates ozone prediction accuracy has been maintained and improved. Seasonal biases in PM2.5, while still present, have been decreasing with model and emission updates. A bias correction procedure is in testing to further reduce biases in the developmental testing of PM2.5 predictions.