Rarely has the continent been covered so extensively with smoke. Canadian wildfires and fires in the Pacific Northwest have conspired to make much of the northern half of the US a hazy, smoky mess. The AIRNOW PM2.5 AQI loop today shows that wide areas of Washington, Oregon and Idaho are impacted by smoke at the Code Red (unhealthy) levels. The MODIS AOD image from AQUA today shows a broad band of very high aerosol optical depth in the prairie states of the US. A small bubble of haze was seen to the southeast of Denver and the trajectories show that it is possible that this smoke came from the northwest at higher levels (1.5 and 3 km) above the surface and at low levels (500m) the trajectory wrapped up the front range to the smoke coming from Canada.
At the DISCOVER-AQ project in Denver, we saw this smoke descend to the surface today at three lidar sites (Fort Collins, Platteville and Golden, CO). The result was elevated PM2.5 up to about 20 µg m-3, not in the hazardous ranges but certainly elevated with respect to what we have seen earlier in the week.
And if there isn't enough smoke here for you, Leonid Yurganov sent along AIRS CO measurements in Siberia from July 17 and Colin Seftor showed the OMPS Aerosol Index readings over the same region today. The Northern Hemisphere is on fire.
Update: July 20, 2014 22:00 MDT
Smoke continues to be the story on Sunday. In AQUA MODIS's AOD image from Worldview (below left), the 1920's Impressionists would have been proud of the painting made by the fires in the Northwest and Canada. VIIRS' palette is a bit more subdued and shows a broad band of AOD = 0.2 across the western states. In Denver, the AERONET DRAGON CIMEL sunphotometers confirm that 0.2 AOD is uniform across the state of Colorado.