October 6, 2008
Haze/Smoke in the Southeast and Mississippi River Valley
PM2.5 air quality is Code Yellow (Moderate) today across much of the Southeast and Mississippi River Valley, as seen in the loop of PM2.5 hourly AQI values (below on left). The Moderate air quality is a result of a widespread diffuse plume of haze and smoke that is entrenched across the region, sandwiched between a stationary front draped east-to-west across the Ohio River Valley and central Mid-Atlantic, and an advancing cold front stretching north-to-south along the Central Plains. The fronts are depicted in the 18:00 UTC surface analysis (below on right) from the Hydrometeorological Prediction Center (HPC); cold fronts are indicated by lines with blue triangles, and the stationary front is indicated by the line with alternating blue triangles and red semi-circles. Air quality north of the stationary front is in the Code Green (Good) range due to the influence of a clean Canadian high pressure system; the center of the high pressure is indicated by the blue “H” over eastern Ontario.
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MODIS true color and AOD imagery are not available today, so I’m working with yesterday’s Aqua images. I’ll update with today’s images when they become available. Diffuse haze and smoke is visible along the Mississippi River Valley, interspersed with clouds, in yesterday’s MODIS Aqua true color image for the continuous United States (below on left). The corresponding MODIS Aqua AOD image (below on right) shows elevated AOD levels in parts of Iowa, Illinois, Missouri, and Arkansas that is associated with the haze/smoke plume.
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The Navy Aerosol Analysis and Prediction System (NAAPS) global aerosol model forecast products for today (below) from the NRL/Monterey Aerosol Page provide additional evidence that the PM2.5 plume is composed of sulfate aerosols (haze) and smoke. The sulfate surface concentration forecast (upper right panel) predicts a wide swath of sulfate aerosols across the eastern United States, while the smoke surface concentration forecast (lower right panel) predicts an area of smoke along the Mississippi River Valley.
