Overview of Air Quality and Aerosol Predictions at NOAA/National Weather Service

NOAA’s National Weather Service (NWS) produces operational air quality predictions of ozone, fine particulate matter (PM2.5) and wildfire smoke for the United States and predictions of windblown dust for the contiguous 48 states. Prediction maps are distributed at https://airquality.weather.gov/ and as a web service at https://idpgis.ncep.noaa.gov/arcgis/rest/services/NWS_Forecasts_Guidance_Warnings. These predictions are available to the general public and to air quality forecasters from state and local environmental agencies, who issue official forecasts for their respective areas. A unified bias-correction procedure was introduced for ozone and PM2.5 predictions when NWS operational prediction system was most recently updated in December 2018.

NWS is moving towards a Unified Forecast System (UFS) (https://ufscommunity.org/) as a source for operational weather prediction applications. The UFS will help streamline and simplify NWS operational suite while including community contributions into a coupled, comprehensive Earth modeling system. To support integration of air quality predictions into the UFS, NWS began testing the Community Multiscale Air Quality modeling system (CMAQ) predictions driven by the operational version of the Global Forecast System (GFS) that has included the Finite-Volume Cubed-Sphere (FV3) dynamical core since June 2019. In addition to system integration, this testing is allowing us to extend ozone and PM2.5 predictions to 72 hours (from 48 hours that operational predictions currently cover). Global aerosol predictions are being unified into the UFS: testing is underway to add them to one member of the Global Ensemble Forecast System (GEFS) in order to replace the current standalone global aerosol prediction system.

Specification of wildfire smoke emissions poses one of the largest uncertainties for prediction of air quality in the United States. Challenges involve detection of fires, the amount and composition of the emissions, altitude of the plume rise, temporal distribution of the emissions and the uncertainty in persistence or change of emissions during the forecast period. Some of the assumptions have been evaluated in several real-time experiments in summer of 2019 during the Fire Influence on Regional and Global Environments Experiment (FIREX). The experiments tested impacts of different fire detection products, different assumptions about the fire duration, fire strength, fuel type as well as influence of long range transport of aerosols into the U.S. domain from the global aerosol simulations.

An overview of recent operational updates and testing of air quality and aerosol predictions will be presented.