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Earth Observation from the Station
 
About 30 years ago, researchers announced that ozone concentrations high in the
atmosphere over the South Pole had hit an all-time low. This critical layer of
the atmosphere that shields us from the Sun's harmful UV rays had a `hole' in
it. And that hole was rapidly expanding. This discovery led to the Montreal
Protocol, an international treaty that regulates production of ozone-destroying
chemicals like chlorofluorocarbons, or CFCs. As a result, the ozone layer is
now on the mend.
 
https://www.youtube.com/watch?v=R83p8sPswqg
 
To study this layer of the atmosphere further, NASA has launched an ozone
sensor to help monitor the long-term change in the ozone layer. Called SAGE
III, short for Stratospheric Aerosol and Gas Experiment III, it will be
installed on the International Space Station in 2017. SAGE III represents the
fourth of a series of instruments that have used similar techniques to measure
atmospheric ozone and aerosols, going back to 1979, with more than 25 years of
on-orbit heritage.
 
The space station's orbit, different from that of most Earth observing
satellites, makes the station a unique vantage point for collecting valuable
data about our planet's health and status. The orbit brings it closer to Earth
and allows instruments onboard to see our planet at different times of day
under varying illumination conditions.
 
NASA is adding to the station's Earth observing capabilities with instruments
like SAGE III. This instrument will monitor ozone all around the Earth at
various times of day and and night, around the globe and during all seasons of
the year, using light from the sun and moon passing through the atmosphere.
 
"Particles (aerosols) and gases in the atmosphere absorb and scatter light to
various degrees depending on their properties," explains SAGE III principal
investigator Pat McCormick. "By measuring the attenuation of light from the sun
as it passes through a section of Earth's atmosphere at spacecraft sunrise or
sunset, we can determine the quantity and location of these aerosols and gases.
Attenuation of sunlight reflected from the moon will be used in similar fashion
for additional data collection."
 
SAGE III will also measure ozone in multiple levels of the atmosphere, reaching
all the way down into the upper troposphere and stratosphere. It will provide a
nearly global picture of the tropospheric ozone, and features improved vertical
resolution over most ozone instruments.
 
McCormick says, "All of this means that SAGE III will provide a very robust and
precise characterization of the ozone layer."
 
Another state-of-the-art instrument -- the Lightning Imaging Sensor (LIS) -
will be installed on station in 2017. LIS will capture real-time total
lightning data over much of the globe -- even over data-sparse regions such as
the oceans -- to support weather forecasting and warnings. The LIS instrument
for ISS is a duplicate of the LIS that operated as part of NASA's Tropical
Rainfall Measuring Mission (TRMM), which completed operations in 2015. From the
station, this new LIS instrument will be able to `look' much farther toward
Earth's poles than it did on TRMM, taking advantage of the station's higher
inclination.
 
Three more instruments are expected to be operating on the station by 2019: the
Global Ecosystem Dynamics Investigation (GEDI), the ECOsystem Space-borne
Thermal Radiometer Experiment on Space Station (ECOSTRESS), and The Orbiting
Carbon Observatory-3 (OCO-3).
 
GEDI will revolutionize the way tropical forests are monitored, shooting laser
beams into tree canopies of the world's forests to take fine-scale measurements
of their height and internal structure. ECOSTRESS will study water use and
water stress in vegetation. The station's orbit will allow ECOSTRESS to take
observations at different times of day across the seasons. OCO-3 will collect
space-based measurements of atmospheric carbon dioxide, to help assess its
distribution and variability.
 
The ISS is a busy place, studying effects beyond Earth and also Earth itself.
 
For more news from the International Space Station, visit www.nasa.gov/station
 
For more science news on and about the Earth, stay tuned to science.nasa.gov
 
 
Regards,
 
Roger

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