June 23, 2014

Southwesterly Winds Transport Saharan Dust into the SE, Humidity Helps Form PM2.5

The country is almost clear of ozone buildup for today, only a few patches of Moderate AQIs over Southern California and the Great Lakes region. The EPA AirNow PM2.5 loop (left) shows a swarm of Moderate AQIs over California and the Southeastern US, elevated levels reaching Code Red (Unhealthy) around the California and Nevada border near Bishop, California as well as in SE Louisiana. The MODIS Terra image (right) also shows high AOD levels in this area and into Nevada. A coastal jet of Southwesterly winds is helping transport Saharan Dust (assumed to be the main cause behind elevated PM2.5 AQIs in Southern Texas) into Louisiana, where the humidity aides in the formation of PM2.5.

Also believed to be a cause of PM2.5 buildup in the Southeastern US are small groups of fires burning in North Carolina and the Mississippi Valley, seen in the Google Earth NOAA HMS imagery (left). The NAAPS model (right) predicts minuscule amounts of smoke over this region, which could help explain why HMS isn't picking up any light smoke except over Indiana, Ohio, and Kentucky. Presumably dust and sulfates are the cause behind the Moderate PM2.5 AQIs over the rest of the Southeast, also predicted in the model. The highest sulfate concentration in the SE was predicted to reach around 16 ug/m3 as well as 60 ug/m3 of dust.

Posted by Farrah Daham at June 23, 2014 9:28 PM
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