Dallas-Fort Worth High Ozone August 14, 2008

• Ozone Animation
• Plume Animation
• Backward Trajectory - CAMS 63 2:00 pm CDT
• Backward Trajectory - CAMS 63 3:00 pm CDT
• Backward Trajectory - CAMS 56 6:00 pm CDT
• Backward Trajectory - CAMS 56 7:00 pm CDT
• Radar Animation
• Satellite Animation
• Satellite Image False Color - Texas East 11:47 am CDT (from UT CSR)
• Satellite Image True Color - Texas East 11:55 am CDT (from UT CSR)
• Satellite Image False Color - Texas East 3:00 pm CDT (from UT CSR)
• Satellite Image True Color - Texas East 3:09 pm CDT (from UT CSR)
• Winds Aloft at Palestine
• Winds Aloft at Palestine Mid-Day

High ozone was measured in the Dallas-Fort Worth area on Thursday, August 14th.   The highest measured eight-hour ozone average was 90 parts per billion (ppb) at the Denton Airport Continuous Ambient Monitoring Station (CAMS) 56.   This measurement rated as Level Orange, Unhealthy for Sensitive Groups, on the U.S. Environmental Protection Agency (EPA) Air Quality Index (AQI) scale.   The highest one-hour ozone measurement was 108 ppb from 2:00 to 3:00 p.m Central Daylight Time (CDT) at Dallas North CAMS 63 and also from 6:00 to 7:00 p.m CDT at Denton Airport CAMS 56.   Nine sites measured AQI Level Orange or higher and exceeded the eight-hour ozone standard out of a total of 18 sites reporting complete ozone data for the day. Moderate or higher ozone levels were reported at 16 sites.    This was the 15th day this year with AQI Level Orange measurement somewhere in the Dallas-Fort Worth area based on the new ozone standard and the eighth day with measurements exceeding the old ozone standard.

Skies were clear all day.   Winds were light and variable early and light from the east to southeast by late morning.   The high temperature reached 105 degrees Fahrenheit (°F) at the Dallas-Fort Worth Airport, 103°F at Dallas Love Field, and 103°F at Fort Worth Meacham Field.

Regional background levels of ozone ranged from about 69 to 80 ppb as indicated by peak eight-hour ozone measurements at Greenville CAMS 1006, Kaufman CAMS 71, Italy CAMS 1044, and Cleburne CAMS 77.   The difference of about 18 to 29 ppb between the measured eight-hour area maximum of 98 ppb and the approximate regional background level was likely caused by local air pollution sources in the Dallas-Fort Worth area.   The estimated local contribution was about 18 to 30 percent of the measured 98 ppb area eight-hour peak.

The Plume Animation shows the estimated plume tracks from large industrial sources of oxides of nitrogen (NOx) and/or volatile organic compounds (VOC), as well as plume tracks for the center of the broad urban plumes coming from Downtown Dallas, Downtown Fort Worth, and other major urban centers.   The plume animation suggests that urban and industrial emissions from the Dallas area were in the vicinity of the highest ozone measurements.