U.S. Air Quality

Special Feature: The Alaska, Yukon and British Columbia Smoke across the U.S.

Introduction

In the middle of June 2004, lightning caused fires in Alaska, Yukon and British Columbia, Canada. The fires were predominantly in Alaska and Yukon. They lasted until the beginning of September. As a result, several large smoke plumes extended westward toward Asia, eastward toward eastern Canada as well as southward and southeastward toward Maryland and even further south reaching Florida. From June 22nd to early September, we monitored the plumes of smoke entering the U.S. and their progress within the country. This special post relates the evolution of the smoke plumes caused by the Alaska and Yukon intense fires, from June to September.

MODIS Rapidfire July 01 2004

The data come from MODIS on Terra and Aqua. They provide the Red Green Blue (RGB) images as well as the Aerosol Optical Depth (AOD) data. Other data come from GOES as well. Some of the images are generated using HDFLook.

Flying with the Smoke

The trip starts in Alaska, Yukon and British Columbia. Fires, first reported on the Smog blog on June 22nd, produce moderate smoke visible in the northwest. The first smoke plume quickly thickens and moves into the U.S. by the northwest. By June 25th, the smoke has reached the northeast of the U.S. The plume is detected with the University of Wisconsin's lidar. Data from the UMBC ELF lidar seem to indicate that the plume also covers the Baltimore region. On June 30th, the smoke passes slightly north of Maryland, toward the northeast, slowly exiting the continent.

The following is a GASP AOD animation showing the Alaska, Yukon and British Columbia smoke near the Great Lakes. The smoke is pushed eastward toward the Atlantic. Gray surfaces represent unavailable data. For comment on how to read similar images, see the help files.

At the beginning of July, the smoke plume startes to dissipate above the U.S. due to a change in wind direction. Winds are blowing westward pushing Alaskan smoke toward Asia. However, the EPA AQI PM2.5 levels are still “moderate” (15.5 ug/m3 to 40.4 ug/m3) in the northeast. On July 2nd, the Smog blog post reports that Fairbanks, AK is under code “maroon” with levels reaching 350 ug/m3 and a visibility as low as 0.8 miles (1.2 km) around noon.

This is the end of the first wave of smoke.

Riding the Second Wave

In early July, another plume enters the country near the Great Lakes region.

GASP AOD July 08 2004

For more information about this particular image see post.

On July 9th, the smoke reaches Baltimore and remains over Maryland for two or three days. The smoke particles linger mainly in the northeast of the U.S. The smoke is visible on the ELF lidar graph at about 2.5 km from the surface. The EPA AQI site shows moderate conditions for the Great Lakes region and the East coast on July 11th.

Near July 16th, the plume gets slowly mixed to cloud systems and is blown away over the Atlantic leaving good conditions over the Great Lakes region and the eastern U.S.

Farewell second wave.

On the Wings of the Third Plume

After almost a month, the Alaska Yukon British Columbia fires are still intense. The particle concentration levels reach 150 ug/m3 near Fairbanks, and some towns have 250 ug/m3. The visibility at Fairbanks drops as low as 3.0 miles at noon. The east/southeast winds push the smoke toward eastern Canada and northeastern U.S.

EPA AQI PM2.5 & IDEA AOD maps July 16 2004

The upper far right image shows the smoke with significantly elevated Aerosol Optical Depth near North Dakota and Minnesota . The U.S. is welcoming the third and most important smoke plume.

On July 18th, the plume extends from eastern Canada to southern Oklahoma. See Dr. McCann post with GASP animations from the 16th to the 19th, showing the smoke progressing southward through the U.S. to the Gulf coast.

3-layer composite of MODIS-Terra/Aqua AOD and MODIS-Terra RGB picture July 18 2004

This is a three-layer composite of Terra and Aqua AOD maps added to a MODIS-Terra RGB image. The color scale has been adjusted to roughly approximate the EPA AQI six-color scale. See layers separately: (Terra)(Aqua)(RGB). For description of AOD images see help files. The RGB image is generated using HDFLook. However see help files for description of similar images.

On the 20th, the smoke reaches UMBC.The plume is now spread all over the mid and eastern U.S. The PM2.5 conditions are moderate in that region.

EPA AQI PM2.5 Map July 20th 2004

The AOD remains elevated over the east coast for several days while the plume is swept eastward toward the ocean Atlantic. IDEA images from the 23rd of July show heavy clouds in the northeast and the smoke plume extending all the way down to southern Florida were the AOD values get very close to 1 (see post). Conditions remain moderate in the east coast with some PM2.5 monitoring sites under code “orange” (40.5 ug/m3 to 65.4 ug/m3). By the 27th, the plume has almost completely been evected out of the continent. The Alaska Yukon fires are still burning and another smaller smoke plume makes its way into the U.S.

Click on the image below to see the movie.

This movie illustrates the advancement of the third major plume into Canada and the US. On the 19th, the plume stretches from the Gulf of Mexico to northeastern Canada. Another plume located in northwest Canada is advancing toward north central US. Notice that from the 21st to the 24th, there is dust coming from Africa approaching Florida (lower right corner). The images are generated using data from MODIS Terra and Aqua. The top layer is produced with Terra data and the bottom layer is created with Aqua data.

Smaller Smoke Plumes

After these three major plumes, smoke still reaches the continental U.S. in smaller plumes until early September. They usually remain in the north until swept away over the oceans. For more detail, see the blog posts for the month of August.

On the 23rd of August, fires are still raging in Alaska, and conditions are very hazardous in Fairbanks with levels reaching 600 ug/m3 and with visibility as low as 0.5 miles (0.8 km). On the 26th, the air quality improves in Alaska. The winds are still blowing westward which decreases the amount of smoke coming into the continental U.S. The visibility at Fairbanks averages 1 mile (2 km).

After these waves of Alaskan and Canadian smoke, started the exceptional dance of tropical storms and hurricanes.

Posted by Kamonayi Mubenga at January 24, 2005 3:10 PM