December 08, 2003
25 Years of TOMS—2003 AGU Fall Meeting
For the last 25 years, NASA’s Total Ozone Mapping Spectrometer
(TOMS) instruments have been looking at ozone and making daily maps of
the ozone content of the atmosphere across the globe, showing scientists
the evolution of the ozone hole from 1979 to today. This data was an
essential factor in establishing international agreements that banned
ozone destroying chlorofluorocarbons and halons. Years of TOMS measurements
and TOMS studies have led to new capabilities and applications for this
instrument: detection of desert dust and biomass burning aerosols, detection
of sulfur dioxide and ash from volcanic eruptions, measurements of low
level ozone or smog, and measurements of UV radiation at Earth’s
surface.
The Antarctic Ozone Hole 2003
TOMS provides dramatic visual evidence of the annual growth and decay
of the Antarctic ozone hole. The ozone losses over Antarctica result
from reactions with the products of man-made chlorine and bromine compounds.
Because of the tilt of the Earth’s axis, continuous darkness falls
at the South Pole from March 21 to September 21. The dark region in the
middle of the July 1 total ozone picture, shown above, is polar night,
where TOMS cannot make measurements. Ozone losses are in blue. Beginning
in August, returning sunlight reaches the edges of Antarctica providing
chlorine and bromine compounds with energy to rapidly destroy ozone.
By mid September, the ozone loss peaks, creating an ozone hole over Antarctic.
Ground Level UV Exposure
Large Ozone hole means more ultraviolet exposure. TOMS tracks solar
ultraviolet (UV-B radiation) measured at 290-320 nanometer wavelengths.
Loss of stratospheric ozone has been linked to skin cancer in humans.
Increased UV-B exposures for Southern continents can seriously impact
phytoplankton and other species. Red is for high UV exposure and blue
is for low UV exposure. For more information on erythemal UV exposure,
click here.
Nearing The Road To Recovery?
Continuous long-term monitoring of ozone levels is crucial in determining
how much ozone loss is attributable to human activities and how much
is the result of natural atmospheric processes. The ozone hole grew larger
throughout the late 1980’s and early 1990’s, as shown in
this time series of maximum areas from 1979 to 2003 (excluding 1995).
Ozone losses are in blue. Last year’s unusual reduction in ozone
losses proved just that — unusual, and not a sign of recovery.
This year the hole reached nearly the same size as 2000 and 2001, larger
than the North American continent. While the manufacture and use of chlorofluorocarbons
(CFCs) and halons that contribute to yearly ozone destruction have decreased,
the chemicals will linger in the upper atmosphere for decades before
the ozone layer will consistently recover.
Arctic Losses Closer To Home
While the Antarctic regularly experiences ozone losses, warmer temperatures
in the Arctic prevent such massive losses from occurring as often near
the North Pole. However, when large Arctic ozone losses occur, the depletion
can threaten populated areas with harmful doses of ultraviolet rays.
Here we show the winters of 1997, 2000, and 2003, particularly severe
losses stretching over populated areas such as Northern Europe. Data
from TOMS-EP.
Polar Stratospheric Clouds
In the stratosphere, 15-50 kilometers (9-31 miles) above Earth, extreme
low temperatures lead to the formation of polar stratospheric clouds.
These clouds of nitric acid-water particles lead to the break down of
ozone and allow harmful ultraviolet rays to reach Earth’s surface.
Extremely low Arctic temperatures enabled polar stratospheric clouds
(PSCs) to last longer during the 1999-2000 winter, causing additional
ozone loss.
Tracking Aerosol — An Unexpected Gift
TOMS was not originally designed to study dust storms, smoke or pollution.
While studying ozone, scientists noticed that something was interfering
with data. That something turned out to be aerosols (very small particles).
NASA Scientists have turned this interference into a very useful product
for studying how aerosols from fires, pollution and dust impact climate.
TOMS is the first instrument to allow observation of aerosols as the
particles cross the land/sea boundary. This data made it is possible
to track a wide range of phenomena such as desert dust storms, forest
fires and biomass burning.
Dust From China to the United States
During spring 2001, TOMS watched a huge dust storm travel halfway around
the world from China to the United States. Scientists use this data to
study how regional ecosystems impact air quality and climate.
California Smoke Trail
In fall 2003, TOMS tracked smoke from the California wildfires. TOMS
observed smoke travel out into the Pacific and turnaround travel across
the United States. TOMS can distinguish among aerosols from fires, dust
and pollution. This distinction allows scientists assess the human and
natural impact on climate change.
Volcanic Ash
When Mt. Pinatubo erupted on June 15, 1991, it was the largest volcanic
event in nearly a century with global consequences. Global average temperatures
were one degree (F) cooler for over a year due to the massive injection
of dust and gases into the upper atmosphere that reflected sunlight,
and stratospheric aerosols increased by over 20 times. In addition, the
protective ozone layer in the upper atmosphere weakened for more than
a year from the gases injected into the stratosphere. Fortunately, the
eruption also marked one of the largest climatic events to be observed
by a fleet of spacecraft, creating one of science’s greatest lab
experiments. TOMS in particular observed the affected ozone and the aerosols,
shown here. The many thousands of tons of sulfur dioxide gas being sent
into the stratosphere were converted to sulfuric acid particles that
helped to reflect sunlight and cool the Earth for a year.
Continuing the TOMS Legacy
TOMS legacy lies on a new satellite called Aura, to be launched in the
spring of 2004. Aura will see ozone in both the upper and lower atmosphere
for the first time. Current missions examine ozone in an isolated part
of the atmosphere, but Aura will track ozone and other gas transport
between the lower and upper atmosphere, giving scientists a more complete
three-dimensional picture of atmospheric ozone distribution. This information
will help scientists understand the long-term health of the upper atmosphere.
Aura’s new sensors will Additionally, Aura carries instruments
with much higher spatial resolution than TOMS. As a result, Aura can
study air quality at a city level.
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Contact:
Wade Sisler
NASA Goddard Space Flight Center
Greenbelt, MD 20771
Phone: (301) 286-6256 |
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The TOMS Satellite
TOMS has flown on three different satellite over the past 25 years, starting
with NIMBUS 7 1978-1993, followed by Meteor 3 from 1991-1994, and Earth
Probe Satellite, shown in this animation, from 1996 to present.
Anarctic Ozone Loss in 2003
From top to bottom: July 1, 2003, August 31, 2003, September 29, 2003,
and November 3, 2003.
Time-Series Animation
July
1 High-Res Image
August
31 High-Res Image
September
29 High-Res Image
November
3 High-Res Image
UV Exposure
From top to bottom: July 1, 2003, August 31, 2003, September 29, 2003,
and November 3, 2003.
July
1 High-Res Image
August
31 High-Res Image
September
29 High-Res Image
November
3 High-Res Image
Time-Series Animation of Ozone Loss from 1979 to 2003
Arctic Ozone Loss
From top to bottom: 1997, 2000, 2003.
Polar Stratospheric Clouds
The clouds in the middle of the photo are polar stratospheric cloud,
or sometimes referred to as mother of pearl clouds. These clouds are
found at altitudes of 60-70,000 feet and are composed of particles containing
nitric acid, water, and sulfuric acid.
Dust From China to the United States
California Smoke Trail
Volcanic Ash from Mt. Pinatubo
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