December 16, 2013

Air stagnation and code red PM2.5 West persists

PM2.5 conditions in Pacific Northwest remained elevated today, peaking in the Code Red (Unhealthy) range in the San Joaquin Valley, Northern California and Oregon (top left). Elsewhere, the Great Lakes, Southwest, and Mid-Atlantic also experienced elevated Code Yellow (Moderate) PM2.5 levels. Finally, Unhealthy (Code Red) Air Quality Indices were observed near Fairbanks and North Pole, Alaska (top right).Even though slightly weaker, the high pressure weather system driving stagnation and limited particle dispersion/mixing in the planetary boundary layer across the Pacific Northwest continues to exacerbate air quality (middle left), however despite slight indication of elevated aerosol optical depth (middle right). Not surprising, hourly PM2.5 measurements at several sites in California and Alaska were considerably high by early afternoon, surpassing 100µg m-3 (bottom).


Posted by Alexandra St Pe at December 16, 2013 6:37 PM
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