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May 31, 2002
NASA SENSORS FIND POLLUTION HIDING IN THE SHADOZ
NASA and scientists from 10 tropical
countries have used balloon-borne
sensors to obtain the first picture of the
structure of ozone (pollution) in the
tropical troposphere, the atmospheric
layer between the surface and 50,000
feet. Under the SHADOZ (Southern
Hemisphere Additional Ozonesondes)
Project, they have found that ozone
"piles up" over the south Atlantic Ocean
due to natural circulation patterns and
that pollution (low-level ozone) from
Africa and South America streams into
the pile-up region, making the ozone
even thicker.
"To envision how the pollution is
moving, think of the Atlantic Ocean as
having a horizontal wheel on either
side, pushing pollution into the middle,
where atmospheric motions are already
dumping ozone. Both pollution and the
pileup are strongest between August
and November," said lead researcher
Anne Thompson of NASA's Goddard
Space Flight Center in Greenbelt,
Maryland. Over the Pacific and Indian
Oceans, the ozone shifts locations with
the waxing and waning of El Niño
cycles. El Niños shift wind circulation
patterns, decreasing the ozone over the
eastern Pacific, and increasing it over
the Indian Ocean.
The new ozone data has come from a 5-year scientific effort in which NASA has
partnered with NOAA, Japanese, Indonesian and Brazilian space scientists and
with researchers in Kenya, South Africa, Java, South Africa, Suriname and four
Pacific islands. Since 1998 more than 1,500 balloons bearing ozone sensors
called ozonesondes have been launched over these tropical locations. The data
are stored in a web-based location designated as the SHADOZ project and are
publicly available.
"Before SHADOZ, ozonesonde launches would stop and start and the data were
not easy to get," said Jacquelyn Witte, co-researcher on the project. By providing
additional sensors to the partners, all the data are collected, shared and
distributed worldwide.
With more ozone over the Atlantic than the Pacific, the additional ozone pileup is
called a "wave-one pattern" that is seen by satellite. The ozonesondes help see
what the satellites do not, and it looks as if the wave one pattern is predominantly
if not exclusively in the troposphere. Thompson said, "This solves a decade-old
mystery about where the Atlantic ozone was coming from."
The SHADOZ project has also been very important to people interested in tropical
climate and meteorology, and those scientists that work on improving satellite
sensors. The ozone data also show that the tropical tropopause - the border
between stratosphere and troposphere - is a 2-mile thick transition layer, not a
sharp boundary as scientists previously thought. Prior to SHADOZ, satellites were
the only way to get this information, and there was no way to verify it. SHADOZ
data will be used to improve satellite instruments by comparing their readings to
those taken from the ground up.
Thompson will present her findings in Session A52B-03, "Variability in Ozone in
the Tropical Tropopause Region from the 1998-2000 SHADOZ Data," at the
American Geophysical Union 2002 Spring Meeting in Washington, D.C., on
Friday, May 31, 2002, at 1:30 p.m., at the Washington Convention Center in
Room: WCC Hall D.
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Contacts:
Rob Gutro
AGU Press Room Washington Convention
Center
(Phone: 202/371-5016)
Cynthia M. O'Carroll
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/614-5563)
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Low-Level Ozone Averaged Over the Global Equator
This graphic depicts a "wave-one" or pile up of
ozone over the Atlantic Ocean each year
between 1998-2000, during the months of
September through November. The graph
basically represents a flattened Earth over the
equator. The left bar represents the height in
the atmosphere where the ozone was found.
The greatest concentration of low-level ozone
was approximately between 6 and 8
kilometers over Ascension (an island in the
Atlantic) and Natal (city on the coast of Brazil)
and with another high peak of low-level ozone
near Reunion (island in the Indian Ocean)
about 8 to 10 kilometers high, as indicated by
the darker colorations in the center of the
image. The ozone concentration is indicated
by ppbv (parts per billion by volume) and
represent the fraction of ozone air particles.
NOTE: Degrees Longitude: The tick marks are
10 degree increments. What is depicted in the
plot is 180 degrees west longitude (the
negatives) to 180 degrees East longitude (the
positive numbers)
NASA Sensors Find Pollution Hiding in the SHADOZ of the Atlantic Ocean
NASA and scientists from ten tropical
countries have used balloon-borne
ozonesonde sensors to obtain the first picture
of the structure of ozone (pollution) in the
tropical troposphere, the atmospheric layer
between the surface and 50,000 feet. Under
the SHADOZ (Southern Hemisphere
Additional Ozonesondes) Project, they have
found that ozone "piles up" over the south
Atlantic Ocean due to natural circulation
patterns and that pollution (low-level ozone)
from Africa and South America streams into
the pile-up region, making the ozone even
thicker.
This graphic shows how the pollution is
moving with easterly winds blowing from South
America pushing pollution into the middle
Atlantic, and westerly winds from Africa also
blowing pollution into the mid-Atlantic, where
atmospheric motions are already dumping
ozone. The arrow depicting the "Walker Cell
Circulation" is a natural movement of air that
rotates in a vertical "circle" from the ocean's
surface to the upper air and back down. This
motion brings pollution from the Pacific Ocean,
and also deposits it over the Atlantic, adding
to the "pile up." Both pollution and the pileup
are strongest between August and November.
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