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Jason-2 begins
mapping oceans
Less than a month
after the launch of the Jason-2 ocean
altimetry satellite, the Ocean Surface
Topography Mission has produced its first
complete maps. The maps were calculated from
the first 10 days of Jason-2’s operational
orbit starting on 4 July.
After reaching its
operational orbit some 1,336 km above the Earth
at a 66º inclination, Jason-2 and its
experimental predecessor, Jason-1, began flying
in formation some 55 seconds apart, making
nearly simultaneous measurements to allow
scientists to precisely calibrate Jason-2's
instruments. Comparisons of the data from the
two satellites show very close correlation of
all measured parameters.
Just 48 hours after the
launch of Jason-2 from Vandenberg Air Force Base
in California on a Delta II launcher on 20 June,
the first waveforms were acquired from Jason-2
and the Centre National d'Etudes Spatiales (CNES),
the French space agency, processed the first
Operational Geophysical Data Record (OGDR) test
product. Following the calculation of the first
Doppler Orbitography and Radio-positioning
Integrated by Satellite (DORIS) preliminary
orbits, the first Interim Geophysical Data
Record (IGDR) product was processed by CNES a
week after launch.
Jason-2’s Ocean Surface
Topography Mission will provide a vital
contribution to the monitoring of climate
change, ocean circulation and weather. Once it
has been calibrated by the partners, the
satellite will provide oceanographic products on
an operational basis to the large EUMETSAT user
community using the European weather satellite
organisation’s proven dissemination
capabilities. The main instrument onboard
Jason-2 is the Poseidon 3 dual frequency
altimeter.
Jason-2 provides the
much-needed data continuity which is essential
when measuring the sea level trend, one of the
key indicators of climate change. Of equal
importance is the contribution Jason-2 will
provide for meteorology and oceanography, in the
area of long-term and seasonal predictions.
Jason-2 is the continuation
of the existing successful cooperation between
the United States and Europe. It is a global
endeavour with responsibilities for satellite
development and launch shared between CNES and
the US National Aeronautics and Space
Administration (NASA). CNES and the US National
Oceanic and Atmospheric Administration (NOAA)
are responsible for satellite operations, while
the Jet Propulsion Laboratory is managing the
mission for NASA. Data processing is being
carried out by CNES, EUMETSAT and NOAA,
depending on the type of product, with EUMETSAT
acting as an interface for near-real-time
product distribution to European users.
EUMETSAT has successfully
processed its first altimetry products following
the installation of the operational version of
the Jason-2 near-real-time processor. EUMETSAT
is responsible for processing Jason-2 raw data
received from the Usingen ground station. Every
day, for seven Jason-2 passes over Usingen, the
processor automatically generates products that
will be used for calibration and validation
activities, an operation that qualifies the data
for further scientific use. Jason-2 raw data
will also be acquired by the NOAA at the Wallops
and Fairbanks ground stations. NOAA will
generate equivalent products from the data.
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