Air quality across the nation was overall good with some exceptions (top left, courtesy of AIRNow). Code Yellow (Moderate) levels were reported in California, the Midwest and southern parts of the country. Code Orange (Unhealthy for Sensitive Groups) PM2.5 levels were reported in California, Idaho, Montana, Michigan, and Louisiana.

GASP EAST AOD reports high AOD values in Louisiana and Tennessee (below). Because of clouds, AOD values in that region and in other regions of the country are not available today.

NOAA's Hazard Mapping System (HMS) reports a large, concentrated area of fires along the U.S and Canada border in the northern part of North Dakota and in the southern part of Saskatchewan and Manitoba, Canada. This large area of fires was observed by myself on my post on 11/14/2009, and by Amy on her post on Tuesday 11/16/2009. In her post, she said that the fires are suspected to be agricultural fires. Fires are also reported in the Deep South, Midwest and West parts of the country. Patches of smoke were reported in Arizona, New Mexico, Texas, Georgia, and in Ontario.  The MODIS Active Fire Mapping Program's large incident map reports two fires here. One fire is in Reno, Arizona and the other fire is in Tintop Missouri.

 

Today most of the country presented good and moderate conditions. Only few states, Montana, Idaho and Oregon read unhealthy levels for sensitive groups (top left). As it was announced by Amy and Ruben previously, the eastern part of the country has read good air quality conditions due to the pass of the extra-tropical cyclone in this area (top right). On the other hand, due to the huge amount of clouds today, it was not possible to obtain AOD information from satellite in the area mentioned. However, high AOD levels were read in Texas, Louisiana and Mississippi in the afternoon (bottom left).

(Special feature) Nasa Earth observatory announced the Resurging of El Niño. Recent measurements of sea level height from the Ocean Surface Topography Mission (OSTM)/Jason-2 oceanography satellite showed that a strong wave of warm water, known as a Kelvin wave, had spread from the western to the central and eastern Pacific (bottom right). This warm wave appears as the large area of higher-than-normal sea surface heights in the area between 170 degrees east and 100 degrees west longitude. Sea surface height is an indication of temperature because water expands slightly as it warms and contracts as it cools. The elevated sea levels in the central and eastern Pacific are equivalent to sea surface temperatures more than one to two degrees Celsius above normal (two to four degrees Fahrenheit).

The extra-tropical cyclone (low pressure system) that was yesterday over the Midwest has moved to over the Eastern US, as seen in the MODIS Terra "true color" (source: UW MODIS Today) image overlaid in Google Earth with today's National Weather Service synoptic analysis (right image). Amy indicated on her post yesterday that the slow moving low pressure and a Canadian high pressure systems would bring cleaner air, improving the air quality. On EPA's Airnow PM2.5 animation one can see the change from Moderate to Good PM2.5 AQI levels, as the low pressure system moved east throughout the day. California and Oregon are experiencing Moderate PM2.5 AQI levels, and according to EPA's Airnow site, an Air Quality Action Day was declared in Klamath Falls, Oregon. The National Interagency Fire Center and NOAA's Hazard Mapping System Smoke and Fire products stated that no fires were active and no signs of smoke and/or dust were visible in the satellite data, respectively.

Air quality conditions in the Eastern United States improved to Code Green (Good) today, with a few areas of Code Yellow (Moderate) in the Ohio River Valley and Southeast, as shown by the loop of preliminary PM2.5 AQI values (below on upper left, courtesy of AIRNow). The haze that Nikisa and Ruben tracked for the past few days has dissipated under the influence of northerly flow generated by an area of high pressure centered over Quebec and an extra-tropical cyclone (low pressure system) over the Midwest. The location of the extra-tropical cyclone is evident in today's Aqua MODIS true color image, overlaid with the synoptic analysis and AQI values (below on upper right in Google Earth). Note that the cloud shield of the system forms a perfect, text-book "comma" shape that is typical of mature extra-tropical systems. The "comma" shape of the system really stands out in a GOES visible image of the US from this afternoon (below on lower left, courtesy of the College of DuPage). Generally Good air quality should continue for the rest of the week in the East, as the low pressure system is expected to move slowly through the area, and the Canadian high pressure system will continue to bring clean, northerly, on-shore flow to the Northeast and northern Mid-Atlantic regions.

PM2.5 conditions are in the Code Orange (Unhealthy for Sensitive Groups) range in several isolated areas of the West today, including Hanford in California's Central Valley, as shown in the loop of preliminary PM2.5 AQI values (below on upper left). Haze is the likely culprit for the elevated PM2.5 values - current weather station observations from the ASOS network (Automated Surface Observing Systems) report haze at Merced and Lemoore, California, with reduced visibility. Smoke has been reported all afternoon at Monterey, but I can't confirm reports of a fire there, or any other source of smoke. Light haze in the Central Valley is apparent in today's Terra MODIS true color image (below on upper right, overlaid with AQI values in Google Earth). NOAA's Hazard Mapping System reports an unusually high concentration of fires in North Dakota and southern Saskatchewan and Manitoba (below on lower left), which they suspect are agricultural fires. So far the fires do not appear to be impacting air quality at the surface. Otherwise, fire activity is relatively quiet this week.

Ruben had a great post yesterday on the Midwestern haze. Refer to that post for his explanation on weather conditions leading to the build up of PM2.5. The Midwestern haze(left image) is now visible over most of the South and Eastern U.S. (particularly dense over Maryland this afternoon). Haze is visible over the Southeast portion of Ontario and Quebec Canada as well. PM2.5 (EPA AIRNow right image) levels are moderate where haze was identified.

Combined PM2.5 and Ozone concentrations varied from moderate to unhealthy for sensitive groups in the West. Skies appeared hazy over Montana, California and the Pacific.

Earlier today the states along the Ohio River Valley were under the influence of a high pressure system. This system allowed warmer southern winds into the region, with temperatures ranging in the mid-60s to low-70s. With the rise in temperature, the PM2.5 AQI reached Moderate and Unhealthy levels (top images), as a temperature inversion formed over the region. The presence of clouds along EPA's region 5 limited the AOD retrieval by the MODIS sensors in Terra and Aqua. Over the locations where the AOD was recorded, values greater 0.5 were observed (bottom left image). PM2.5 concentration timeseries (bottom right image) from ground monitors in Alleghany County, PA and Indiana show that concentrations as high as 111 and 52.9 ug/m3, respectively, were recorded. According to the National Interagency Fire Center and NOAA's Hazard Mapping System Smoke and Fire product indicated that no fires were active and no signs of smoke and/or dust were visible in the satellite data, respectively. Moderate PM2.5 AQI levels were also reported in California and Oregon.

Haze is visible over the Midwest region again (left image; UW MODIS Direct). The haze was particularly dense earlier in the morning. A similar episode was reported last Saturday. The actual source is currently unknown. However, local sources such as residential wood burning may be contributing to the load. Aerosol transport from the North and West is also speculated (see visible haze over Montana and Canada in left image) Ground based PM2.5 and Ozone (right image; EPA AIRNow ) are moderate in this region as well. The NAAPS team suggests that most of the Midwestern haze is due to sulfates.