87th AMS Annual Meeting

Wednesday, 17 January 2007: 10:30 AM
NOAA-EPA's National Air Quality Forecast Capability: Testing Expanded Capabilities
212A (Henry B. Gonzalez Convention Center)
Paula M. Davidson, NOAA/NWS, Silver Spring, MD; and J. T. McQueen, R. Mathur, R. Draxler, R. A. Wayland, N. Seaman, and K. Carey
Current Operational Capabilities: In partnership with the US EPA, NOAA has implemented the early phases of a national air quality forecast capability. The initial operational implementation in September, 2004, provided ground-level ozone predictions only for northeastern US. In August 2005, the operational domain was extended to the entire Eastern US. Predictions are generated with linked weather and air quality models run operationally at NOAA's National Centers for Environmental Prediction (NCEP): the NOAA-EPA Community Multiscale Air Quality (CMAQ) model driven by NOAA's operational North American mesoscale weather prediction model (NAM), converted in June 2006 from the earlier Eta-12 model to the Weather Research and Forecasting Nonhydrostatic Mesoscale Model (WRF-NMM) in NCEP operations. The capability is an end-to-end system providing twice daily predictions of hour-by-hour ground-level ozone concentrations through the next day at 12km resolution, disseminated on NWS and EPA servers. Near-real-time verification is conducted with AIRNow observations.

Experimental Capabilities: Two expanded capabilities are being tested experimentally: 1) ground-level ozone predictions over a coast-to-coast (CONUS) domain, available since June, 2006, and 2) semi-quantitative smoke predictions, available since March 2006. Improvements to the expanding ozone capability, along with conversion of NAM from Eta-12 to the new WRF-NMM, and updated CMAQ, include: better coupling between NAM and CMAQ, with options for increased vertical resolution; updated emissions estimates, and improved vertical mixing. Systematic differences between predictions with the earlier Eta-based and current WRF-based systems for the operational domain over Eastern US are minor; on average WRF-based predictions of daily maximum ground-level ozone concentrations are a few ppb lower. For the separate experimental capability over CONUS, however, early summer testing with the 2006 system upgrades shows systematic underprediction of ozone concentrations, in contrast with overprediction generally found in earlier Eta-based developmental testing. Efforts to diagnose and address the underlying causes are underway. In addition, an experimental smoke forecast guidance tool is being tested with 1-day forecasts of hour-by-hour smoke predictions at 12km resolution, updated once each day. Preliminary analysis, facilitated with near real-time smoke-column verification from satellite products, shows promise based on 1-day forecasts for smoke from early-season grass fires. This tool integrates satellite information on location and extent of wildfires with USFS estimates of fire emissions, NAM weather prediction and HYSPLIT dispersion prediction to simulate smoke transport.

Developing Capabilities: Also in progress are efforts to develop a quantitative particulate matter forecast capability. Currently the NOAA-EPA team is developmentally testing ground-level aerosol predictions, using a modified CMAQ capability and pollutant data from emissions inventories only. Early test results will be summarized. Research is ongoing to develop capabilities for real-time quantitative ingest of additional emissions sources important for quantitative predictions of particulate matter. Targeted deployment of nationwide ozone forecasts within 3 years will be followed by the addition of quantitative particulate matter forecasts, and extended forecast periods - out to day 2 and beyond.

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