June 26, 2012
Code Purple in Texas due to combined smoke and ozone.
The first image below, courtesy NOAA HMS, shows the fire locations across the United States. The red dots correspond to active fires, and the grey areas are plumes. The largest concentrations of fires is in the Midwest region, with smoke plumes covering most of the central part of the country. The animation below, courtesy GASP shows the increase AOD from these fires. You can see the smoke moving throughout the day, mostly moving southward.
 |  |
The first animation below is the EPA AIRNOW AQI values for Houston and the surrounding areas. During the daytime hours, you can see the AQI values greatly rise. From 14:00 - 16:00 CDT there is actually a code purple for very unhealthy levels of air pollution. These unsafe levels of air quality are shared between the smoke debris from fires in the area and increased levels of ozone formed in the urban areas. When you have a day like today, that was extremely hot and had very low cloud coverage, there will be a surge of ozone production near factories and major highways. The data and graph below show the hourly surface ozone (ppb) for the Houston area. You can see that it reached almost 150 ppb in some areas (looks like ambient values ~40 ppb).
 |  |
The first image below shows the NOAA ozone forecast for Texas. You can see the large increase in ozone near Houston, specifically you can see a stripe of very high ozone being transported directly into the Gulf of Mexico. The second image, courtesy CALIPSO, shows the swath that was essentially stretched from Texas to the Dakotas. You can see that there are layers of aerosols between 3 and 5 km. This is most likely due to smoke particulates aloft. The AIRS dust score does not show any dust along this swath and most of the AERONET size distribution retrievals were dominated by the fine mode, so I would assume that this smoke particulates aloft.
 |  |