December 1, 2012

Weekend edition: PM is elevated throughout much of the east

AIRNOW's AQI shows that PM levels will be moderate from the Mississippi to the east coast. Some areas of Pennsylvania are forecasted to reach the Unhealthy for Sensitive Groups stage today (thanks to Bill Ryan for the forecast). We don't have all the MODIS panels yet today but there is a greyish pall over much of the Mississippi Valley and Ohio Valley states.

By this afternoon, the haze on the MODIS AQUA red-green-blue (RGB) composite was notable in Maryland. The NESCAUM CAMNET Webcam image in Baltimore (below right shows that the view of the Key Bridge indicates visibility of under 20km. The Aerosol Optical Depth from the UMBC CIMEL Sunphotometer today was 0.5 in the green channel.

Update: December 2, 2012

The PM2.5 readings in Maryland yesterday were positively summerlike, but there was limited sunlight available so the aerosols were unlikely photochemically driven. You can get secondary sulfate in moist environments through cloud conversion processes involving peroxyde radicals. Given the fog in the air we saw this morning (and in the lower Chesapeake bay yesterday), wet conversion processes of SO2 to sulfate are likely. This wintertime pollution event is interesting.

Note to Blogmaster: since categories are not posting, we need to do a patch to Movable Type... this affects Browsers post Firefox 16.0

Posted by Ray Hoff at December 1, 2012 12:18 PM
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