Joint NASA-French Satellite to Track Trends in Sea Level, Climate (OSTM/Jason 2)
- From: baalke@xxxxxxxxxxxxx
- Date: Tue, 20 May 2008 17:36:28 -0700 (PDT)
May 20, 2008
Steve Cole
Headquarters, Washington
202-358-0918
stephen.e.cole@xxxxxxxx
RELEASE: 08-132
JOINT NASA-FRENCH SATELLITE TO TRACK TRENDS IN SEA LEVEL, CLIMATE
WASHINGTON -- A satellite that will help scientists better monitor
and
understand rises in global sea level, study the world's ocean
circulation and its links to Earth's climate, and improve weather and
climate forecasts, is undergoing final preparations for a June 15
launch from California's Vandenberg Air Force Base.
The Ocean Surface Topography Mission (OSTM)/Jason 2 is a partnership
of NASA, the National Oceanic and Atmospheric Administration (NOAA),
the French Space Agency Centre National d'Etudes Spatiales (CNES) and
the European Organisation for the Exploitation of Meteorological
Satellites (EUMETSAT). The mission will extend into the next decade
the continuous record of sea-surface height measurements started in
1992 by the NASA-CNES TOPEX/Poseidon mission and extended by the
NASA-CNES Jason 1 mission in 2001.
The satellite will continue monitoring trends in sea-level rise, one
of the most important consequences and indicators of global climate
change. Measurements from TOPEX/Poseidon and Jason 1 have shown that
mean sea level has risen by about 0.12 inches a year since 1993,
twice the rate estimated from tide gauges in the past century. But 15
years of data are not sufficient to determine long-term trends.
"OSTM/Jason 2 will help create the first multi-decadal global record
for understanding the vital roles of the ocean in climate change,"
said OSTM/Jason 2 project scientist Lee-Lueng Fu of NASA's Jet
Propulsion Laboratory in Pasadena, Calif. "Data from the new mission
will allow us to continue monitoring global sea-level change, a field
of study where current predictive models have a large degree of
uncertainty."
Developed and proven through the joint efforts of NASA and CNES,
high-precision ocean altimetry measures the height of the sea surface
relative to Earth's center to within about 1.3 inches. These
measurements, also known as ocean surface topography, provide
information on the speed and direction of ocean currents. Because sea
surface height is strongly influenced by the amount of heat in the
ocean, it also is an indicator of ocean heat storage in most places.
Combining ocean current and heat storage data is key to understanding
global climate variations.
OSTM/Jason 2 marks the transition of high-precision altimetry data
collection to the world's weather and climate forecasting agencies.
Scientists soon will be able to forecast how ocean circulation will
change from one season to the next and how that circulation is linked
to climate change and weather patterns.
"What began as an investment by NASA and CNES in research tools for
studying the ocean has matured into a proven technique that will now
be routinely used by the world's weather and climate agencies to make
better forecasts," said Michael Freilich, director of the Earth
Science Division in NASA's Science Mission Directorate in Washington.
"People in coastal areas will benefit from improved near-real-time
data on ocean conditions, while people everywhere will benefit from
better seasonal predictions resulting from the increased
understanding of Earth system processes enabled by these
measurements."
OSTM/Jason 2 will ride to space aboard a NASA-provided United Launch
Alliance Delta II rocket, entering orbit about six to nine miles
below Jason 1's 830-mile-high orbit. OSTM/Jason 2 will use its
thrusters to raise itself into the same orbital altitude as Jason 1
and move in close behind its predecessor.
The two spacecraft will fly in formation, making nearly simultaneous
measurements. For the six to nine months after launch, scientists
will verify the instruments are calibrated precisely. OSTM/Jason 2
then will continue Jason 1's former flight path, and Jason 1 will
move into a parallel ground track midway between two OSTM/Jason 2
ground tracks. This tandem mission will double the amount of data
collected, further improving tide models in coastal and shallow seas,
and helping researchers better understand ocean currents and eddies.
OSTM/Jason 2's mission is designed to last at least three years.
The CNES-provided OSTM/Jason 2 spacecraft carries five primary
instruments similar to those on Jason 1. Its main instrument is the
CNES-provided Poseidon 3 altimeter. NASA's Advanced Microwave
Radiometer measures atmospheric water vapor, which can distort the
altimeter measurements. Three location systems combine to precisely
measure the satellite's position in orbit: NASA's Laser
Retroreflector Array and Global Positioning System payload, and CNES'
Doppler Orbitography and Radio-positioning Integrated by Satellite
instrument. Instrument improvements since Jason 1 will allow
scientists to monitor ocean coastal regions with increased accuracy,
nearly 50 percent closer than in the past. Three experimental
instruments round out the payload: CNES' Environment Characterization
and Modelisation-2 and Time Transfer by Laser Link, and Japan's Light
Particle Telescope.
JPL manages the mission for NASA's Science Mission Directorate. After
on-orbit spacecraft commissioning, CNES will hand over mission
operations and control to NOAA. NOAA and EUMETSAT will generate,
archive and distribute data products.
For more on OSTM/Jason 2 on the Web, visit:
http://www.nasa.gov/ostm
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