David E. Steitz
Headquarters, Washington, DC
(Phone: 202/358-1730)

Cynthia O’Carroll
Goddard Space Flight Center, Greenbelt, MD
(Phone: 301/614-5563)

Lee Tune
University of Maryland, College Park, MD
(Phone: 301/405-4679)

RELEASE: 01-43

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

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. More information is available on the Internet