New research sponsored by NASA may soon help scientists do a better job of tracking pollution plumes around the world and help provide people more advance warning of unhealthy air.
Researchers have discovered that smoke and smog move in different ways through the atmosphere. A series of unusual events several years ago created a blanket of pollution over the Indian Ocean. In the second half of 1997, smoke from Indonesian fires remained stagnant over Southeast Asia while smog, which is tropospheric, low-level ozone, spread more rapidly across the Indian Ocean toward India.
This situation was exacerbated by El Nino, which had already increased the thickness of smog over the region. At the same time, additional smog from African fires streamed over the Indian Ocean and combined with the smog from Indonesia, creating an aerial canopy of pollutants.
Researchers tracked the pollution using data from NASA's Earth Probe Total Ozone Mapping Spectrometer (TOMS) satellite instrument. "TOMS is the only satellite instrument that follows both smoke and smog, globally," said Anne Thompson, NASA Earth Scientist at Goddard Space Flight Center, Greenbelt, MD. "The extreme pollution generated during the Indonesian fires was the first time we saw smoke move more slowly and in different directions from where smog moved." Although TOMS has been observing the atmosphere since 1978, new air-quality technologies added in 1997 enabled scientists to see the divergence of smoke and smog for the first time.
The different movement occurred because the pollutants were in different layers of the atmosphere. Heavier smoke particles stayed close to the region of the fires while smog moved more quickly and spread over a large area. "Typically, smog is seen coming from Africa because much more burning occurs there, but in 1997 the Indonesian plume was thicker due to the fires there," Thompson added.