Advances in National Air Quality Forecast Capability’s Fine Particulate Matter (PM2.5) Predictions

NOAA’s National Air Quality Forecast Capability (NAQFC) provides operational air quality predictions over the next 48 hours for ozone, fine particulate matter (PM2.5) and wildfire smoke over the United States (U.S.) and predictions of airborne dust over the contiguous 48 states. Prediction maps are displayed at http://airquality.weather.gov and their distribution through a web enabled map service is currently in testing. Ozone and PM2.5 predictions are produced using a system operationally linking Community Multiscale Air Quality (CMAQ) model with meteorological inputs from the North American Mesoscale Forecast System (NAM). Smoke and dust predictions are produced using NOAA’s Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model.

The updates to NAQFC predictions that focused on advancing predictions of PM2.5 and were implemented in June 2017 will be overviewed. Both HYSPLIT and CMAQ model are now driven by the new version of NAM 4.0, and include wildfire smoke emissions from a newer version of the USFS BlueSky system. The newer version 5.0.2 of the CMAQ system is configured to initialize by rerunning it over the previous 24 hours to include wildfire emissions at the time when they were observed from the satellites, to better represent wildfire emissions prior to beginning 48 hour predictions. Post processing to reduce the bias in PM2.5 predictions has been further refined using the Kalman filter analog (KFAN) technique to better capture day-to-day variability. Dust related aerosol species at the CMAQ domain lateral boundaries are updated to use the NEMS Global Aerosol Component (NGAC) v2 forecasts.

Further testing has begun to extend CMAQ ozone and PM2.5 predictions to 72 hours. Fire emissions data from Environment and Climate Change Canada (ECCC) are being tested for inclusion over Canadian portions of model domains. To better represent the oil and gas activities influencing the surface ozone concentration, an impact study to estimate a possible upper bound of oil and gas activities was initiated. Finally, the KFAN technique is being modified and tested to improve ozone predictions.