Dallas-Fort Worth High Ozone June 23, 2008

• Ozone Animation
• Plume Animation
• Backward Trajectory - Denton Airport CAMS 56 4 pm CDT
• Backward Trajectory - Eagle Mountain CAMS 75 4 pm CDT
• Satellite Animation
• Satellite Image True Color - Texas 2:35 pm CDT (from UW SSEC)
• Radar Winds from Palestine
• Radar Winds Mid-Day from Palestine

High ozone was measured on the northwest side of the Dallas-Fort Worth area on Monday, June 23rd.   The highest measured eight-hour ozone average was 86 parts per billion (ppb) at the Eagle Mountain Continuous Ambient Monitoring Station (CAMS) 75.   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 103 ppb from 3:00 to 4:00 p.m Central Daylight Time (CDT) at Denton Airport CAMS 56.   Three sites reached AQI Level Orange and exceeded the eight-hour ozone standard, out of 19 sites reporting complete ozone data for the day.   Moderate or higher ozone levels were reported at 17 sites.   This was the ninth day this year with AQI Level Orange measurements somewhere in the Dallas-Fort Worth area based on the new ozone standard and the fifth day with measurements exceeding the old ozone standard.

Skies were clear to partly cloudy, and winds were light from the south in the morning and increasing from the southeast in the afternoon.   The high temperature reached 100 degrees Fahrenheit (°F) at the Dallas-Fort Worth Airport, 97°F at Dallas Love Field, and 98°F at Fort Worth Meacham Field.

Regional background levels of ozone ranged from about 61 to 69 ppb as indicated by peak eight-hour ozone measurements at Kaufman CAMS 71, Italy CAMS 1044, and Cleburne CAMS 77.   The difference of about 17 to 25 ppb between the measured eight-hour area maximum of 86 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 20 to 29 percent of the measured 86 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.