In 2001, Washington State University ’s Laboratory for Atmospheric Research (LAR) produced one of the first numerical air quality forecast systems in the country. This air quality forecast modeling framework, called the Air Indicator Report for Public Awareness and Community Tracking (
AIRPACT) has been continually enhanced, and it currently provides 48-hr air quality forecasts over the Pacific Northwest at a resolution of 4 km. It uses regional meteorological forecasts generated by the Weather Research Forecast (WRF) model operated by the University of Washington, which is then fed into the Community Multiscale Air Quality (CMAQ) model to predict air quality. For a better air quality forecast, AIRPACT computes hourly anthropogenic and natural emissions including wildfires emissions with the SMARTFIRE2 daily fire activity information. The wildfire season in Pacific Northwest has been a particularly challenging period to provide a reliable air quality forecasts. For instance, AIRPACT-5 tends to underestimate surface level fine particulate matter (PM2.5) concentrations, primarily result of errors in organic matter aerosols.
To improve wildfire-related air quality forecasting in AIRPACT-5, we have integrated new knowledge gained from wildfire measurements for secondary organic aerosols (SOA) and its contribution to the total mass of PM concentrations. We implement a) improved chemical speciation and emission factors for VOCs and PM2.5 in AIRPACT, based on recent observations including FLAME-IV (fourth Fire Lab at Missoula Experiment), and b) updated SOA modeling into the AIRPACT-5 modeling system. The updated AIRPACT system is evaluated against the airborne measurements such as the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS) and the Biomass Burning Observation Project (BBOP), which measured a detailed air quality information from the fires occurred in the Pacific Northwest in summer 2013.