Welcome
As we prepare to meet the challenges of
global climate change and pollution, we urgently need to
improve our understanding of the atmosphere's chemistry.
TES is making a vital contribution to this effort as one
of four instruments aboard NASA's
Aura
satellite. TES focuses on the troposphere, the layer of
atmosphere that stretches from the ground to the
altitude at which airplanes fly. With very high spectral
resolution, TES can distinguish concentrations of gases
at different altitudes, a key factor in understanding
their behavior and impact. It's the first orbiting
instrument able to do this with ozone, a very important
chemical with regard to both global warming and air
pollution.
Chemical clues
After the sun warms the Earth, the
planet radiates that energy back into space in a range
of infrared wavelengths. But before reaching space, the
energy passes through the atmosphere, where various
gases absorb and re-radiate portions of it -- in effect
stamping the energy with their own spectral signatures.
From its vantage point in orbit, TES measures radiation
coming out of the top of Earth's atmosphere in a range
that includes the signature wavelengths of ozone, carbon
monoxide, water vapor, and methane. Those data enables
scientists to deduce valuable information about global
warming and climate change, Earth's water cycle, and air
pollution on a local, regional, and global
scale.
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Ozone
Ozone's impact is all about location.
High in the stratosphere, ozone shields us from the
sun's harmful UV rays. But beneath that, at the top of
the troposphere, it acts as a greenhouse gas and
contributes to global warming. In the middle of the
troposphere, it plays a key role in a chemical process
that cleans the air of certain pollutants. But at the
bottom of the troposphere, where we live and breathe, it
contributes to smog and is toxic to plants and animals.
TES lets us track the abundance, creation, destruction,
and movement of this critical chemical at various
altitudes in the troposphere.
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Global warming and climate change
Greenhouse gases contribute to global
warming by trapping some of the energy that Earth
radiates after being warmed by the sun. TES scientists
are currently able to calculate how much energy is
trapped at various altitudes by ozone and they're in the
process of doing the same with water vapor, the most
abundant greenhouse gas. Upcoming work with TES data may
similarly reveal the effects of
methane.
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Global water cycle
Understanding how water travels between
Earth's surface and atmosphere is crucial to being able
to predict the climate and the availability of water in
various parts of the world, and to formulating plans to
help people adapt to climate changes brought about by
global warming. TES helps to deepen our understanding of
the water cycle by providing one important piece of the
puzzle.
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Biomass burning
Biomass burning is the widespread
practice, especially in the tropics, of using fire to
clear forests and grassland for agriculture and to
dispose of crop residue. Among its environmental
impacts, biomass burning releases large amounts of
carbon monoxide (CO) into the atmosphere, where it
reacts with other chemicals to produce ozone. Other
instruments observe and measure CO, but only TES
measures both CO and ozone -- at the same time and at
various altitudes. This enables scientists to see the
extent to which biomass burning contributes to ozone in
the troposphere.
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Local and regional air pollution
TES feeds data about ozone
concentrations to local agencies and decision-makers,
and helps them use the data in climate-modeling tools.
Since TES is the only remote-sensing instrument
currently flying that can distinguish ozone at altitudes
where it does harm from altitudes where it is
beneficial, TES data can be uniquely valuable to local
and regional air-pollution analysis and
forecasting.
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What is TES?
TES is an infrared spectrometer flying
aboard the Aura satellite, which currently orbits Earth.
Its high spectral resolution enables it to measure
concentrations of ozone, carbon monoxide, water vapor
and methane at various altitudes in the atmosphere,
which reveals important information about global warming
and climate change, the water cycle, and air
pollution.
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Detecting altitudes
Every kind of chemical absorbs and emits
a characteristic pattern of energy wavelengths that
serves as its spectral fingerprint. These wavelengths
vary slightly with the changes in temperature and air
pressure found at different altitudes. TES' predecessors
were not sensitive enough to detect those variations,
but TES has such high spectral resolution, it can tell
the difference between the wavelength pattern of a
chemical at one altitude from the pattern of the same
chemical at a different altitude. This makes the
instrument uniquely valuable for measuring ozone, for
example, which is harmful at some altitudes and
beneficial at others.
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Nadir and limb views
TES observes both straight down (nadir
view) and at an angle that just skims the surface of the
planet (limb view). Each view has its advantages. Limb
viewing provides a much longer path through the
atmosphere, and looking through a larger mass of air
improves the chances of observing sparsely distributed
substances that might be missed in the nadir view. Limb
viewing's angle also makes it easier to determine the
altitudes of the observed chemicals. But nadir viewing
is less obscured by clouds, is able to reach the lowest
parts of the troposphere, and enables scientists to
study changes across distances as short as tens of
kilometers.
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Validation
Quantities measured by TES are
rigorously compared with other measurements that
represent the state of the atmosphere. Validation
includes comparisons of satellite observations, in situ
measurements and chemistry and transport models, each of
which represent the state of the atmosphere in different
ways. Validation helps scientists quantify systematic
errors, and can provide constraints for atmospheric
models into which TES data are
assimilated.
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News And Events
Pollution on the Move
AURA satellite instrument teams (TES & OMI) track the path of ozone from a major source - China, the world's biggest greenhouse gas emitter.
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NASA's TES Satellite Instrument Gives New Insight into Water Cycle
Satellite measurements give a better understanding of what happens to rain and snow that fall on land, with a few surprising findings.
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Ozone pollution from near and far
Tropospheric ozone is generated from precursor pollutants, but can be blown far afield.
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Rollover and/or click on the graphics
on and around the globe above
for more info on the TES Mission highlights