December 17, 2013

Elevated AQI in California due to PM 2.5, most likely nitrates.

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 major concentration of fires is in the Southeast region, Texas and Pacific Northwest region. Although there is a large concentration of fires, there is little smoke being picked up by HMS. The next image shows the retrieved AOD image for the day, courtesy GASP EAST. The image shows an increase in AOD in the Southeast and Texas regions, which most likely corresponds to some of the local fires.

The next image, courtesy EPA AIRNOW, shows the AQI values the Southwest region. There is an increase in the AQI values due to PM 2.5 at the surface. As mentioned above, overnight temperature inversions will reduce atmospheric mixing, and light winds will limit pollutant dispersion. These conditions, combined with pollutant carryover from day to day, have yielded Unhealthy for Sensitive Groups particle levels for the region (yesterday and tomorrow as well). The next image, courtesy OMI NRT, shows the retrieved NO2 column for the troposphere. This image shows a large amount of NO2 in this same region as the elevated AQI values. This enhancement in column NO2 shows a strong correlation with the increase in PM 2.5 at the surface.

Posted by John Sullivan at December 17, 2013 6:24 PM
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