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Satellite Altimetry Status & Products – Part 1
J. Lambin, CNES
G. Dibarboure, CLS
Satellite altimetry:
users needs as seen by space agencies
■ One « high accuracy » reference mission
 TOPEX/Poseidon , Jason series (including Jason-3) => to be continued by
Jason-CS?
 Payload required:
 Dual-frequency altimeter,
 Microwave radiometer,
 Precise orbit determination suite (GPS, DORIS, laser)
 Orbit
 Minimizing tide aliasing: non-sunsynchronous, mid-inclination
 Suitable for POD (high altitude)
 Data latency: 3h / 2 days / 2 month
■ One at least (ideally 3) other altimetry missions (ERS, GFO, ENVISAT…)
 less demanding POD => post-calibrations using reference mission, SSO OK
 Mesoscale oriented => better spatial coverage, but longer cycles
■ Future generation / alternatives
 Swath altimetry: SWOT
 Constellations (Iridium-NEXT?)
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Ocean Surface Topography Constellation Roadmap
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Medium accuracy SSH from high-inclination sun-synchronous orbit
HY-2A China
HY-2B, -2C, -2D
Saral/AltiKa India/France
ERS-2 ESA
ENVISAT ESA
Sentinel-3B, -3C, -3D
Sentinel-3A Europe
CRYOSAT-2 ESA
GFO NOAA
GFO-FO NOAA
Swath altimetry from high-inclination orbit (several orbit options)
SWOT/WaTER-HM USA/Europe
Orbit to be assessed
Jason-CS successor Europe/USA
High accuracy SSH from mid-inclination orbit
Jason-3 Europe/USA
Jason-1 Fr./USA
Jason-CS/Jason-4 Europe/USA
Jason-2 Europe/USA
In orbit
Approved
Planned/Pending approval
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Needed
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Current altimetry missions
■ Jason1: in extended mission, fully
operational
 Moved to interleaved orbit with Jason-2 in
Jan/Feb 09, after 6-month « formation flying
phase »
 Vulnerable to equipments failure risk
■ Jason-2: lauched in June 2008,
 OGDR distributed operationally since Dec
2008,
 IGDR distributed operationally since Jan 2009
 GDR will be released after OSTST (July 2009)
 DUACS products already available
 Very good product quality
Jason-1 vs Jason-2 SSH differences
■ ENVISAT
 excellent synergy with Jason1 (T/P and ERS
complementarity further improved)
 S-band missing: degraded quality by lack of
ionospheric delay correction
 Will be put on a drifting orbit in 2010
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DUACS map of SLA – J1+J2+EN
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SARAL/AltiKa
■ Cooperative framework : CNES/ISRO
■ Altimetric Gap filler between ENVISAT & SENTINEL3
 Research oriented mission :
 new, higher frequency, greater performance
 potential new applications on ice, land, coastal areas
 …but with a consolidated architecture : conventional altimeter
■ Tentative launch date : mid- to end-2010
■ Payload:
 AltiKa: Ka-band altimeter (higher accuracy, no need for a 2nd frequency)
+ Dual-frequency radiometer (sharing the same antenna)
 POD: DORIS/LASER
■ Orbit: same as ENVISAT (sun-synchronous, 35-day cycle)
■ Data policy : ~ the same as JASON missions (through CNES/ISRO RAs)
 Next India/France scientific workshop on 3-5 december in Ahmedabad
 International Research Announcement planned in 2009
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Sentinel-3
■ ESA mission, in the frame of GMES
program
■ Mission Profile:
 7-year lifetime (consumables for 12
years)
 SSO orbit (10h descending), 27-day
repeat cycle, 98.65°
■ Satellite Payload:
 Ocean and Land Colour Instrument
(OLCI)
 Sea and Land Surface temperature
(SLST)
 Sentinel-3 Ku/C Radar Altimeter (SRAL)
 Dual Frequency MicroWave Radiometer
(MWR):
 POD: GPS/DORIS/Laser
■ Products: 3h / 1-2 days / final after POD
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HY-2A mission description
■ Chinese oceanographic mission (+ French
participation)
■ Launch planned Sept 2010
■ Payload:
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Dual-frequency altimeter Ku/C
nadir 3-frequency radiometer
5-frequency scanning radiometer
Wind/wave scanning scatterometer
DORIS/GPS/LRA
geodetic orbit after 3 days
■ Orbit (sun-synchronous 6-18, 99.35°):
 First 2 years with a 14-day cycle
 Then one year with geodetic orbit (168-day
cycle, 5-day approx. subcycle)
■ Products availability?
 Through DUACS multi-mission products (not
confirmed yet)
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One day of the 14-day orbit
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Cryosat-2
■ ESA mission, to be launched in Nov 2009
■ Objective: to determine fluctuations in the
mass of the Earth’s major land and marine
ice fields
■ Mission description:
■ Lifetime 3 years + 6 month comissioning
■ Orbit
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Star Trackers
Magnetometer
SIRAL
Antennas
LEO, non sun-synchronous
Repeat cycle: 369 days (30 d sub-cycle)
Mean altitude: 717 km
Inclination: 92°
■ Spacecraft and Payload recurrent from lost
CryoSat 1
■ Instruments
 SIRAL (SAR/Interferometric Radar Altimeter):
Thermal
Radiator
 Low-Resolution / SAR / SARIn modes
 KU-band (single frequency, no radiometer)
 POD from DORIS and laser
Laser
Retroreflector
DORIS
Antenna
S-Band
Communications
Antenna
X-Band
Downlink
Antenna
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■ Ocean data availability not confirmed yet,
studies under way
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Jason-3
■ NOAA/EUMETSAT cooperation with CNES & NASA contributions
 CNES in-kind contribution : Proteus platform , system engineering, and manpower equivalent to
JASON/OSTM (i.e. about one third of European part of the program)
 Launch : mid-2013
■ Mission design: Jason-2 like
■ Pending approval (in December 2009)
… and Jason-CS?
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Surface Water & Ocean Topography (SWOT)
•Mission combining research needs
associated to hydrology and oceanography :
- mapping of water level for rivers, lakes,
and oceans (including coasts)
•Principle : Wide-swath interferometric,
Ka-band altimeter
•Recommended by the US Decadal Survey
•Submitted in the frame of the Cnes Scientific Prospective Seminar (march, 2009)
•Cooperation scheme : TBD (NASA/CNES/…)
•Phase 0 in 2007, pre-phase A & phase A in 2008/2009
•Launch possible in ~2016
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Conclusions
■ There is a rich panel of missions under development or planning => let us
wish they will all succed!
■ Space agencies (NASA, CNES) tend to put as priority innovative missions
 Promising in a long term perspective, but
 Potential issues in the continuity of the long-term record
 Some effort is required to secure the transition to operational agencies of
already mature concepts
■ Multiple missions decided/developed by multiple agencies/countries
 Coordination not guaranteed, higher programatics risk
 Data availability on a case-by-case basis
 Efforts from CEOS (through NOAA and EUMETSAT) to improve altimetry mission
coordination
■ GODAE could (and should) be more vocal about their needs
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CNES involvment in altimetry
experiment
Complementing mission
mesoscale, ice
ERS-1 (ESA)
Altimeter algorithm
ERS-2 (ESA)
ENVISAT (ESA)
DORIS
Altimeter Processing
Archive & distrib.
HY-2 (CNSA)
DORIS
Reference mission
Ocean Large scale
TOPEX/POSEIDON
(CNES/NASA)
Launcher
DORIS & POSEIDON
Mission Center
Jason-1 (CNES/NASA)
Satellite bus
DORIS & POSEIDON
Control & Mission Center
ALTIKA/SARAL
(CNES/ISRO)
Altimeter, radiometer,
DORIS, Lra
Process, archive & distrib.
Sentinel-3A (ESA)
DORIS
operational
Jason-2 / OSTM
(CNES/NASA/EUMETSAT/NOAA)
Satellite bus
DORIS & POSEIDON
Control & Mission Center
Earth reference system
1990
SPOT2 (CNES)
DORIS
SPOT3 (CNES)
DORIS
SPOT4 (CNES)
DORIS
SPOT5 (CNES)
DORIS
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2005
CRYOSAT (ESA)
DORIS
PLEIADES (CNES)
DORIS
CRYOSAT2 (ESA)
DORIS
2010
SALP : Altimetry and precise positioning service
MERCATOR : assimilation, forecast
CNES / SHOM / METEOFRANCE / IFREMER / CNRS / IRD
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