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A
10-Year Flight Through the Atmosphere
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| The
Earth's ozone hole on November 30, 2000. | | |
The
upper atmosphere is a virtual treasure trove of scientific finds. It affects Earth's
climate at the same time as providing a signal of what's to come for us. NASA's
Upper Atmosphere Research Satellite (UARS) has been exploring the atmosphere for
ten years and helping scientists understand everything from its chemistry to the
Sun, to the ozone layer and El Nino. Designed to operate only two years, its major
discoveries include mapping of chemicals in the atmosphere, understanding causes
of ozone depletion like CFC's and measurements of UV levels from the Sun.
UARS
SPACECRAFT (Click on titles for Quicktime movie)
The Upper Atmosphere
Research Satellite (UARS) has outlived its planned lifetime by operating for 10
years with seven of its 10 instruments continuing to function. UARS' primary mission
is to measure ozone and chemical compounds found in the ozone layer, which affect
ozone chemistry and processes. It also measures winds and temperatures in the
upper atmosphere (stratosphere) as well as energy from the Sun.
OZONE CONTRIBUTIONS (mpeg
movie)
Pictured are the largest Antarctic 'hole' (2000) and the region of
low ozone over the Arctic, which reached its high in 1999. In 2000 UARS scientists
found that the Arctic ozone may not be recovering as quickly as previously thought.
They attributed this to more than expected polar stratospheric clouds forming
high above the Arctic. They provide the vehicles which convert benign forms of
chlorine into reactive, ozone-destroying forms but they also remove nitrogen compounds
that act to moderate the destructive impact of chlorine. UARS
also facilitated the first study to link greenhouse gases to increased ozone depletion
over populated areas in 2001. Scientists detected increasing water vapor in the
stratosphere resulting partially from greenhouse gases that may delay ozone recovery
and increase the rate of climate change. The study worked because scientists were
able to best simulate the behavior of temperature and ozone in the upper atmosphere
when adding water vapor data from UARS into the climate model. UARS'
CHEMICAL CONTRIBUTIONS - Quicktime
movie of side by side comparisons of chlorine monoxide and CFCs Quicktime
of ozone hole
Within a few months of launching, UARS mapped various chlorine radicals over the
Antarctic. The key version, chlorine monoxide, it is a prominent ozone-destroying
radical. Chlorine monoxide, or (ClO) can occur naturally but is usually a by-product
of harmful pollutant CFCs entering into the upper atmosphere. Here the theories
linking the presence of chlorine monoxide and depleted ozone are confirmed. UARS
was first to map the major chemical components of the upper atmosphere (stratosphere).
THE
SUN-EARTH CONNECTION (Quicktime movie)
Two of UARS' instruments measure
small changes in the solar UV spectrum and a third records the Sun's total energy
output. They contributed to discoveries such as finding a link between the energy
given off by the Sun and Earthly wind patterns that facilitate climate changes.
UARS let scientists take into account solar activity on the ozone layer and the
chemistry of the upper atmosphere where it gets absorbed. Earlier
this year, UARS also allowed scientists to watch the same solar energy take a
toll on the ozone layer by actually working to destroy a portion in the lower
atmosphere and a small amount of the crucial upper atmospheric ozone layer. The
energetic particles hitting the camera on the second image break down ozone molecules
in much the same way as CFCs. These images of the Sun were taken with the Solar
and Heliospheric Observatory (SOHO). TRACKING
VOLCANIC EFFECTS (Quicktime movie)
One of the most destructive volcanic
eruptions of our century occurred a few months before UARS' launch. Mt. Pinatubo's
eruption in 1991 provided UARS with an opportunity to study the impact of volcanic
eruptions on the upper atmosphere (stratosphere). After various chemical reactions,
twenty million tons of sulfur dioxide spewed out by Pinatubo resulted in a blanket
of aerosols up to 30 times higher than aerosol concentrations measured six years
later. In fact, for over a year, global temperatures were one degree (F) cooler
and the ozone layer was weakened due to the massive injection of dust and gases
into the upper atmosphere.
KEEPING CURRENT ON OCEAN EVENTS Quicktime
movie of El Nino anomaly MPEG
movie of a morph between peak El Nino and La Nina As
almost a bonus, the UARS science team discovered that the MLS instrument on UARS
could measure water vapor in the lower atmosphere. This was valuable in 1997 when
the team noticed unusually high amounts of vapor and correctly predicted a strong
El Nino season. El Nino affects global weather patterns such as flooding and mild
winters in the U.S. Data from the TOPEX/Poseidon satellite helped create this
view where red signifies very warm temperatures and purple is cool.
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