The Wallow Fire in Arizona is producing a massive pall of smoke that has extended over several states in the Southwest and Midwest of the United States, as the uncontrolled blaze burns thousands of acres and forces evacuations of nearby towns. Nitrogen oxides are one of the main gaseous products of combustion, and they can be measured by satellite instruments. The Ozone Monitoring Instrument (OMI) on NASA's Aura satellite is an excellent detector of nitrogen oxides, providing a NO2 data product that can be used to visualize the sources of these gases to the atmosphere.
The OMI image at upper right shows the NO2 plume from the Wallow Fire extending into New Mexico. As the smoke rises, the NO2 in the smoke plume is more easily detectable than at ground level, which is why the heaviest concentrations are seen over New Mexico, rather than over Arizona. This image merges data acquired over the period June 6-8, 2011.
A larger view of the Colorado and New Mexico region over June 6-8, shown below, indicates three distinct sources of NO2. The northern source in Colorado is the city of Denver, which is known for a "brown cloud"of haze and pollution that forms due to temperature inversions caused by the flow of colder air from the adjacent Rocky Mountain range. Even though Denver has been somewhat successful in reducing the occurrence and severity of air pollution, the large city is still clearly a major source of nitrogen oxide pollution.
The southern source seen in this image is the NO2 from the Wallow Fire.
On the border of Colorado and New Mexico, NO2 from a third source is visible. This NO2 stems from two coal-fired power plants in New Mexico, the Four Corners Steam Plant and the San Juan Generating Station. The Four Corners Steam Plant is one of the largest coal-fired power plants in the United States, generating 2,040 megawatts of electricity, and producing an estimated 45,000 tons of nitrogen oxides per year. According to the Environmental Protection Agency (EPA), the Four Corners plant is the largest single source of nitrogen oxides in the U.S.
Due to this large amount of nitrogen oxide emission, and the proximity of the plant to many national parks and forests (including the cliff dwellings of Mesa Verde National Park), and pressure from environmental groups, the EPA has proposed controls that will reduce nitrogen oxide emissions from the Four Corners Steam Plant to only 9,000 tons a year.
Below the OMI NO2 image are two animations of smoke from the Wallow Fire generated by the NASA GES DISC Hurricane Data Analysis Tool, which provides Merged IR data from geostationary operational environmental satellites (GOES). These animations were created from data acquired on June 4 and June 8; thunderstorms are seen building on the eastern side of the image on June 4. The smoke plume becomes more visible as the Sun rises higher in the sky over the region. Also see related links below the animations.
Acknowledgment: OMI data is archived at the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), and is provided by KNMI, the Koninklijk Nederlands Meteorologisch Instituut (Royal Netherlands Meteorological Institute). Dr. P.F. Levelt is the Principal Investigator of OMI, Dr. J. Tamminen is the Finnish Co-PI, and Dr. P.K. Bhartia leads the U.S. OMI science team. Dr. James Gleason (NASA) and Pepijn Veefkind (KNMI) are PIs of the OMI NO2 product.
OMI NO2 data product visualized with the NASA Giovanni system, for the period June 6-8, 2011. The three main sources of NO2 in this image are, from top to bottom: Denver, Colorado; the Four Corners Steam Plant and San Juan Generating Station in New Mexico; and the Wallow Fire in Arizona.
Merged IR animations from GOES satellites: June 4 (left), June 8 (right). Click on either image to view larger. The brightness of the smoke in the June 4 image may be due to the formation of pyrocumulus above the fire.