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NASA
SATELLITE TRACKS HAZARDOUS SMOKE AND SMOG PARTNERSHIP
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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.
Between July and November 1997, the emissions from the Indonesian
fires caused considerable air pollution throughout the Southeast
Asian region, including Indonesia, Malaysia, and Singapore.
Hazardous particles found in smoke caused air-quality and
health problems throughout the region including asthma, upper
respiratory infections, decreased lung function, and eye and
skin irritation.
Before the fires began in 1997, the El Nino and changing atmospheric
patterns over the Indian Ocean, a pattern called the Indian
Ocean Dipole, caused the ozone column to thicken, indicating
that climatic factors play a major role. When scientists went
back and looked at the 1980s El Nino events, they noticed
the same behavior.
"However, we can detect no trend in smog ozone during the
1980s in the tropics, even though burning may have increased,"
said Thompson. "In some regions of the tropics, rising ozone
precedes the burning period and in other regions, ozone levels
don't rise as much as we would expect during the local burning
season. Clearly, factors other than biomass burning exert
a strong influence on tropical tropospheric ozone."
Since 1978, TOMS has eyed upper and lower level ozone in Earth's
atmosphere. Since upper-level ozone in the stratosphere over
the tropics is uniform, TOMS can subtract it out from its
readings and calculate the smog in a "column" of atmosphere
that stretches from the surface to the tropopause, more than
40,000 feet high.
A paper titled "Tropospheric Ozone and Biomass Burning,"
by Goddard's Anne Thompson and researchers at the University
of Maryland; Science Systems and Applications, Inc.; and Hokkaido
University of Japan, explaining the divergence of the pollutants,
appears in the March 16 issue of Science.
This research was conducted by NASA's Earth
Science Enterprise , a long-term research effort dedicated
to studying how human-induced and natural change affects our
global environment.
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These are images of the area in close up. From left
to right, top to bottom, are July 6, August 11, September
16, and October 22. Please click on each image
to enlarge the image.
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These
are images of the area in wide screen. From left to
right is July 6, August 11, September 16, and October
22. Please click on each image to enlarge the image.
For
medium resolution images:
For
high resolution images:
Movies
have been generated:
Close
up of the area over time from July to October
Wide
angle of area over time from July to October
Zoom
of area over time from July to October
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