February 22, 2019 - 2:00 pm
February 22, 2019 - 3:00 pm
Address120 David L Boren Blvd, Room 5600Norman, OK 73072 View map
Meteorological Conditions During an Ozone Episode in Dallas‐Fort Worth, Texas, and Impact of Their Modeling Uncertainties on Air Quality Prediction
Co-authors Ming Xue and Fanyou Kong
The southern Great Plains experiences an unhealthy level of ozone (O3) at times. Some of the O3 events coincide with passages of Atlantic hurricanes. The contributing factors for these O3 events remain unknown. A severe O3 pollution event on August 27, 2011 in the Dallas-Fort Worth (DFW) area, associated with passage of Hurricane Irene, is investigated in this study with a combination of observations and simulations using the Weather Research and Forecasting model with Chemistry (WRF/Chem). During the O3 episode, a stationary front with a stagnant zone at the leading edge, associated with the passage of Irene, persisted to the west of DFW. The stagnant zone confined the pollutant plume originating from DFW, leading to accumulation of primary pollutants and prominent O3 formation. Emission sources from a few urban areas east of DFW as well as power plants near Mt Pleasant and Carthage also partially contributed to this DFW O3 pollution episode. Such a scenario on August 27 is different from the typical summer days over the southern Great Plains when southerly winds prevail along the west edge of the Bermuda high and the pollutant plumes from DFW are extended downstream, resulting in low O3. Ensemble WRF/Chem predictions driven by the operational Short-Range Ensemble Forecast outputs are conducted to examine the impact of meteorological uncertainties (particularly transport uncertainties) on air quality forecasting. The ensemble mean gives a better prediction in terms of plume directions than individual members, which is critical for public health analysis.