Ozone Episodes in Austin, TX

METEOROLOGY DATA (1984 -1992):

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 Wind Roses Quick Link _(TCEQ)

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Interpreting Wind Rose Details

The data and the software used to make the plots, called "WRPLOT," were obtained from the U.S. Environmental Protection Agency (EPA). Information on each wind rose details the — frequency of occurrence of winds shown in each of 16 direction sectors (north, north-northeast, northeast, etc.) and six wind speed classes for a given location and time period; station identification, month, and period of record located at the top left of each wind rose; percent frequency of calm wind located in the lower left side of the wind rose plot; and color scheme used for wind speed categories depicted at the bottom left of each wind rose plot. Wind roses can sometimes be used to graphically depict the dominate transport direction of the winds for an area. Due to the influences of local terrain, possible coastal effects, exposure of the instruments, and temporal variability of the wind, the wind rose statistics may not always be representative of true transport for an area. Other meteorological conditions may also be important for determining the formation and transport of certain atmospheric contaminants, particularly reactive pollutants. In general, air quality is often correlated with the dominate transport direction of the wind. The wind rose then provides the best information regarding the percentage of time the direction(s) and speed(s) associated with a certain air quality can be expected over a long period of time. Similarly, wind roses can be compared to trajectories. The general direction of the trajectory and the wind rose can be compared to obtain a qualitative assessment of how frequently that particular trajectory might be expected over a long period of time.

Ozone Episodes in Austin TX (Back Trajectories, 32 hours)

September 2000

Peak Austin Ozone and Meteorological Data (Murchison) during September 15, 2000 through September 18, 2000

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August 2000 (Back trajectories, 32 hours)

Peak Austin Ozone and Meteorological Data (Murchison) during August 31, 2000 through September 7, 2000

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1999 and 2007 Base Case

1999 Episode Animation

September 1999 Episode Ozone Plume - 1999 Base Case	September 1999 Episode Ozone Plume  - 2007 Base Case

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Sensitivity Runs

September 1999 Episode

 

A zero-out modeling simulation is one in which emissions from a region of interest are eliminated (or "zeroed-out") in order to evaluate the impact of regional transport from one urban area to another. In the Austin zero-out run, anthropogenic VOC, NOx, and CO emissions were eliminated from the five-county Austin area (Travis, Williamson, Hays, Bastrop, and Caldwell counties). The Comprehensive Air Quality Model with Extensions (CAMx), a 3-dimensional photochemical grid model developed by ENVIRON International Corporation (ENVIRON), was then used to evaluate the effects on both 1-hour and 8-hour average ozone concentrations within the Austin area.

Austin "Zero-Out" Runs

Episode Days: September 15th - September 20th 1999

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  Click below buttons for the 24h animation

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San Antonio "Zero-Out" Runs

Episode Days: September 15th - September 20th 1999

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Houston "Zero-Out" Runs

Episode Days: September 15th - September 20th 1999

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1999 September Episode, Aircraft data 

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July 1995 Episode 

July 1995 (Back trajectories, 32 hours)

Peak Austin Ozone and Meteorological Data (Murchison) during July 7, 1995 through July 12, 1995

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