Update to and Recent Performance of the NAM-CMAQ Air Quality Forecast Model at NCEP operations

NOAA and EPA have developed and operationally implemented a new ozone forecast capability, in response to Congressional direction. The NWS/ National Centers for Environmental Prediction (NCEP) Eta model at 12 km was used to provide meteorological predictions for the EPA Community Multi-scale Air Quality (CMAQ) model to produce 48 h ozone predictions. The CMAQ system simulates various chemical and physical processes that are important for modeling atmospheric trace gas transformations and distributions.

This paper describes the improvements to and performance of the NOAA Eta-CMAQ modeling system that are run on the NWS/NCEP operational computer center for real-time air quality forecasting. Two systems are tested and evaluated in the Summer 2005; the Eastern U.S domain and CONUS runs. The Eastern U.S. domain is run twice per day at 12 km resolution at 06 and 12 UTC with forecasts to 48 hours. This year the system was run with updates to the both the Eta-12 and CMAQ modeling systems including 6 hour cycling for initial CMAQ conditions, use of the NCEP Global Forecast System (GFS) ozone predictions (Lee, et al, 2004) to prescribe CMAQ upper lateral boundary conditions, and updates to the CMAQ model cloud scheme and emissions. Both experimental and developmental systems were run with gas-phase chemistry only, however, research runs were made over the Eastern U.S. with aerosols turned on. The Eta models land surface model was also upgraded and its effect on air quality forecasts will be summarized.

A general model evaluation compared against the EPA AIRNOW observation network will be performed using the NCEP Forecast Verification Systems (FVS) for the various regions of the Country. Finally, future plans will be described that include the transition of the Eta-CMAQ system to WRF and inclusion of particulate forecasts into NCEP operations.