Looking at the NOAA HMS Smoke and Fire Product (top left), the small red dots indicate clumps of fires in the Midwest and parts of the Southeast. The EPA AIRNow combined AQI loop (top right) sees moderate AQIs in these areas, but also USG and Unhealthy AQIs to the West. Unhealthy AQIs started in the Southernmost portion of California and eventually moved to where we currently see them, near Salt Lake City with a current high AQI of 163.
The MODIS Terra image (bottom left) has a lot of cloud cover, but it does not show any elevation in AOD in the Southwest or Southeast to explain the AQIs. But looking at the OMI NRT tropospheric NO2 column (bottom right), the Southwest is seeing higher values of NO2, and it looks as though PM2.5 is the culprit for the AQIs. The national park webcams detail clear skies to the West, so stagnant air could be a possible contributor to the poorer air quality today.
Posted by Graham Antoszewski at December 13, 2013 11:15 PM