Note:

Ozone concentrations in the above plots are in parts per billion (ppb) and are one-hour averages for the hour beginning at the time indicated on the plot.

Wind vectors shown in the above plots are plotted to scale, so that the length of the vector corresponds to the distance traveled by the air during the hour of measurement. The vectors are plotted from the station circle toward the direction from which the wind was blowing and show approximately where the air that arrived at the end of the hour was located at the beginning of the hour. Wind speeds have been adjusted upward based on annual wind speed averages as compared to sites with the best overall wind exposure. This adjustment approximates the wind speed at typical daytime ozone transport altitudes of 500 to 5,000 feet above ground level and has also been applied to the plume determinations. Because of limited vertical mixing before about 9:00 a.m. CDT, the portion of each plume emitted before this time tracks only air pollution emissions that were in a shallow layer extending to no more than about 200 to 300 feet above ground level.

Plumes shown in the above plots are approximations of the plume positions at the end of the clock hour shown. The plume positions are estimated based on wind measurements made at about 30 feet above ground level from the real-time air monitoring sites in the area and track air pollution emissions released since 1:00 a.m. CDT. The large circles indicate the origin of each plume and the smaller circles indicate hourly positions along the plume. The lines connecting the circles represent the centerline of the plume. The plumes are color coded based on the facility total of oxides of nitrogen (NOx) and volatile organic compounds (VOC) from the TCEQ emissions inventory. The color scale is shown below.

Plume Color Indicates Origin Facility NOx and/or VOC Total:
Bright red - 10,000 or more tons per year NOx or 5,000 or more tons per year VOC
Bright magenta - 7,000 to 9,999 tons per year NOx or 4,000 to 4,999 tons per year VOC
Dark red - 4,000 to 6,999 tons per year NOx or 3,000 to 3,999 tons per year VOC
Dark blue - 2,000 to 3,999 tons per year NOx or 2,000 to 2,999 tons per year VOC
Gray - 1,000 to 1,999 tons per year NOx or 800 to 1,999 tons per year VOC
Dark Cyan - Urban core plume centerlines (representing very broad plumes)