June 27, 2008
Very Unhealthy Air Quality in California Continues
Air quality continues to range from Unhealthy for Sensitive Groups (Code Orange) to Unhealthy (Code Red) and Very Unhealthy (Code Purple) across Northern California and the Central Valley. Very high levels of both ozone and PM2.5 are contributing to the extremely poor air quality conditions. The images below show the loop of ozone readings (on the left) and PM2.5 readings (on the right) in California today.
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Today’s MODIS Terra true color image of the AERONET Moss Landing region (below on left) clearly shows the widespread smoke, seen as grey and defuse across the Central Valley and flowing off the Pacific Coast. Note that the brighter white areas along the coast are clouds from the “June Gloom” marine layer. The corresponding MODIS Terra AOD image for Region 9 (below on the right) shows the very high AOD levels from the smoke across California.
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Dry and stagnant conditions are expected to continue into Saturday, providing no relief for those affected by the wildfires. The National Weather Service has issued a Red Flag warning for the Southern Sierra Nevada region from Yosemite to the Fresno/Tulare County line until 8 PM PDT Saturday. A Red Flag warning means that critical fire weather conditions are either occurring now, or will occur shortly. An air stagnation advisory is also in effect for all of interior California until 11 AM PDT Monday. Winds are transporting smoke from the numerous wildfires across the region into the San Joaquin Valley, leading to the current high ozone and PM2.5 levels. The 48-hr MODIS/NAM aerosol trajectory forecast (shown below on the left) indicates that particulates from the wildfires will likely continue to remain relatively localized at the surface, which will probably keep air quality in the Unhealthy range over the region for the next several days. The view from Turtleback Dome at Yosemite National Park, elevation 5266 feet, taken today at 2:30 PM PDT, gives an idea of the reduced visibility due to smoke from the fires.
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Across the rest of the country, air quality is in the good to moderate range. Conditions are hazy in Florida and the Gulf of Mexico, likely due to transport of African dust across the Atlantic, as Nikisa told us yesterday and Tuesday. The image below on the left shows today’s MODIS Terra true color overlaid with the 21:00 UTC AQI readings for the Florida region. PM2.5 air quality is Code Yellow across much of Florida, likely due to the impact of the African dust. The GASP AOD animation for Region 4 (below on the right) shows the elevated AOD levels over southern Florida and over the Atlantic associated with the dust.
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