Smoke, discussed by Ana yesterday (also read older posts), is dense today over the Midwest/Great Lakes (left image-Terra MODIS; UW MODIS Today). The aerosol load is quite intense; AOD (right image; NOAA UMBC GASP IDEA) estimated from the MODIS instrument is 0.6 in most places. Air quality is not any better in this region. Today’s air quality map from EPA AIRNow indicates that most of the in situ sites, relative to this event, measured mostly “moderate” (code yellow) AQI. We can see, by looking at the EPA map, that air quality conditions are primarily good along the East coast. These aerosols will likely continue to blow eastward which will eventually affect surface AQI on the East. Refer to EPA AIRnow national outlook and IDEA forecasts.

It was easy to visualize the smoke today with MODIS Terra and Aqua over the same regions Meloe spotted in yesterday's post. Shown at the top are MODIS imagery of the north-central US (left) where moderate to thick smoke can be seen over both Dakotas, Montana, an Wyoming. There is also thick smoke over Oregon and Washington and southwestern Canada (right). At the surface (bottom) air quality ranged from good to yellow, and it appears the smoke may be worsening surface air quality in the northwest. The few monitor data over the north central U.S were in the good range, but monitor coverage is not as good so it is not as easy to assess the effect of the smoke there at the surface.

Today’s MODIS AQUA RGB image (top, left) shows a widespread smoke plume over the states of Washington, Indiana, Montana, Northern Utah and the Canadian border. A large fire activity in Oregon still reported by the National Interagency Fire Center seems to be partly contributing to those hazy conditions. Today’s HMS map (top, right) also shows a smoke plume but spread out further east.
MODIS AOD values are unfortunately not available today and GASP AOD retrievals (bottom, left) are very strong over Oregon and Washington. Those values should be carefully handled as it could be due to cloud contamination. This smoke event seems to occur aloft as it contributes, at the most, to “moderate” air conditions in the west northern states according to today’s EPA AIRNow’s PM2.5 map (bottom, right).

On another hand, “unhealthy for sensitive groups” conditions are reported in the surroundings of Los Angeles, southern California (PM2.5 Map). The rest of the country shows “moderate” air conditions scattered over the eastern part of the US. Ozone levels are mostly “good” except over southern California and Tennessee where they are “moderate”(Ozone map).

Today’s Terra MODIS image shows widespread smoke throughout Oregon, coastal Washington, and extreme northern California (below left, see smoke circled in yellow). According to the NOAA Hazard Mapping System, the fires are burning in Hood River, northeast Douglas and extreme western Klamath counties in Oregon and in western Siskiyou and eastern Del Norte counties in California. The smoke is mostly moderately dense to dense and moving to the west and northwest. The NOAA GASP AOD today confirms the presence of smoke in this area, as shown by the aqua, yellow, and red areas in the image below right.

Looking at ground-based values, AIRNow shows that air quality is generally good to moderate around the country. The exceptions are Code Orange PM2.5 (Unhealthy for Sensitive Groups) in Oakridge, Oregon (which actually reached Code Red, or Unhealthy, earlier today), and Cleveland, Ohio (which also reached Code Orange). See AIRNow PM2.5 readings as of 4:00 p.m. EDT, below left. Ozone was elevated to Code Orange in the Central Valley of California as of 5:00 p.m. EDT (2:00 p.m. PDT), probably a few hours before its peak value for the day. See AIRNow ozone values, below right.

EPA and NASA, in conjunction with Battelle Memorial Institute and Sonoma Technology, Inc., issued an Air Quality Story yesterday on the wildfires in the western U.S. that we have been discussing on the Smog Blog for the past week. Air Quality Stories are a combination of informative graphics and associated text that are distributed to various media outlets and other interested parties. The stories cover current air quality events ranging from wildfires to regional haze events, and include discussions on the potential health effects of the air quality event. Below are the image and text for yesterday's story on the wildfires and elevated ozone levels in California and Orgeon.

Air Quality Story: Western U.S. Wildfires September 15-17, 2008

Several large wildfires continue to burn in the western U.S. Two fires currently impacting air quality are the Tehipite and Rattle wildfires. The fine particles in smoke have a direct impact on particle pollution levels; in addition, the gases in smoke can react with sunlight to form ozone.

The Tehipite Fire in the Kings Canyon National Park in central California was started by lightning on Monday, July 14. The fire has burned 5,554 acres so far and is impacting air quality in the San Joaquin Valley, where AQI levels have ranged from Unhealthy for Sensitive Groups (Code Orange) to Unhealthy (Code Red) over the past few days. The Rattle Fire, located near Toketee Falls, Oregon, was started by lightning on Monday, August 18, and has burned 5,733 acres. This fire has caused Moderate (Code Yellow) AQI levels in parts of Oregon.

A high pressure system over the region for the past several days led to reduced vertical mixing and warm to hot temperatures. These conditions were conducive to both fire activity and poor air quality. Tuesday and Wednesday, an upper-level trough of low pressure building into the western U.S. will bring cooler temperatures and enhanced vertical mixing, causing air quality levels to improve. Tuesday, Unhealthy for Sensitive Groups (Code Orange) AQI levels are expected in central California and Good (Code Green) AQI levels in Oregon. Moderate (Code Yellow) AQI levels are expected in central California and Good (Code Green) AQI levels in Oregon on Wednesday.

Health Tip: When you see or smell smoke, cut back on strenuous activities and follow your local news for additional information.

Sources:
Environmental Protection Agency (EPA)
National Aeronautics and Space Administration (NASA)

Today continued yesterday's trends with little change. Ozone activity as shown on AirNow was relatively uneventful for the day, except for central California which experienced Code Orange (unhealthy for sensitive groups) in the late afternoon.

Across the Eastern half of the country the Air Quality Index was uneventful mostly green with a few yellow spots, as displayed on this Google Earth image containing MODIS Today and AirNow AQI information:

However, there are still fires and their associated smoke affecting some Western areas. The NOAA Smoke Text product noted that the very northern portions of California, western Oregon, eastern Washington, and western Idaho were experiencing moderate to dense smoke due to the wildfires that were discussed yesterday. The NOAA hazard mapping system shows the predicted extent of these plumes below:

This smoke plumes can be seen on this MODIS Today Image, with the corresponding Aerosol Optical Depth (AOD) data from NOAA’s IDEA:

Interestingly, the smoke has had only a marginal effect on PM2.5 readings, with only a few scattered code yellow (moderate) and orange (unhealthy for sensitive groups) readings cross the upper Northwest on this animation from AirNow:

Air quality was Code Green (Good) today across most of the country, as seen in the hourly loops of AQI values for ozone (below on left) and PM2.5 (below on right). The exception is on the West Coast, where high pressure is creating conditions conducive for elevated ozone and PM2.5 levels. Both pollutants were in the Code Yellow (Moderate) and Code Orange (Unhealthy for Sensitive Groups) range across regions of California and Oregon today.

The fires in western Oregon and northern and central California that we have been discussing on the Blog for the past week continued to burn today. Smoke plumes from the fires are evident in the MODIS Aqua true color image for the USA1 region from the MODIS Today website (below on left). Today’s MODIS Terra AOD image (Aqua data aren’t available for the West Coast at this hour) for Region 10 from the IDEA site (below on right) shows elevated AOD levels associated with particulates from smoke plumes associated with the fires.

Weather conditions in the West make it likely that the fires will continue on Tuesday, and new fires may be sparked. The National Weather Service (NWS) has issued Red Flag Warnings for much of Oregon, western Washington, and parts of California for tonight and tomorrow, as shown by the magenta pink areas in the map of NWS watches and warnings (below). A Red Flag Warning means that critical fire weather conditions are occurring now… or will occur shortly. High pressure and strongly subsiding air along the West Coast are creating very low relative humidities and high temperatures. In some areas, relative humidity values will be <10% for 10 hours or more, creating the potential for explosive fire growth.