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1WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
TOPEX and JASON SPACEBORNE ALTIMETERS
TOPEX and JASON SPACEBORNE ALTIMETERS
Jean PLA
CNES, Toulouse, France
2WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Scope of a spaceborne altimeter Frequency plan for TOPEX and JASONUsage of the dataData Assimilation and forecasting
Summary
3WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Topex-Jason Mission Objectives: Scope of a spaceborne altimeter
• Ocean general circulation
• Intra-seasonal to interannual sea level variations
• Long term mean sea level changes
• Tide observation
• Wind speed mapping and significant wave height at the ocean surface
4WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Objectives of a spaceborne altimeter
5WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
TOPEX/POSEIDONJASON 1JASON 2
6WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Jason-1500 kg
performances similar to in-flight T/P ones
TOPEX/POSEIDON2500 kg
7 Dec. 2001
TOPEX/POSEIDON (1992) ; JASON-1 (2001) ; JASON-2 (2007-2008)
7WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Frequency plan of TOPEX/ JASON altimeters• C BAND: 5140 to 5460 MHz, 320 MHz bandwidth, linear frequency modulation
• Fc = 5.3 GHz, antenna gain = 32.2 dBi (3.4° at -3dB), peak power = 17 W, mean power = 0.54 W, PRF = 300 Hz, pulse duration = 105.6 μs
• 5140 MHz to 5250 MHz, under 4.4: no allocation to EESS (active), no recorded cases of interference
Services: Aeronautical Radionavigation Fixed Satellite (Earth to Space): feeder
links of non- GSO satellites in the mobile satellite service
Mobile• WRC(2003): extension from 5460 MHz to 5570 MHz
• Ku BAND: 13415 MHz to 13735 MHz: 320 MHz bandwidth, linear frequency modulation
• Fc = 13,575 GHz, antenna gain = 41.5 dBi (1.23° at -3 dB), peak power = 8 W, mean power = 1.52 W, PRF = 1800 Hz, pulse duration = 105.6 μs
• 13250 MHz to 13750 MHz: allocation to EESS (active):• Other services: Aeronautical Radionavigation
Space Research
• For C and Ku BANDS: use of large bandwidths (320 MHz) to estimate ionospheric delay and to get unprecendented accuracy: around 1 cm
8WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
JASON-1
Altitude = 1344 km, beam footprint = 77 km
9WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Jason-1 InstrumentJason-1 Instrument
10WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Radiometer (JMR)
This instrument collects the natural emission by the ground surface and in the atmosphere at three different (18, 21 and 37 GHz) frequency bands. The goal is to determine the water vapour content and in liquid water in the atmosphere, when combining the whole set of measurements within those bands. Therefore, it is possible to know the correction to be applied to the altimetric measurement. ( NASA)
11WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
From GEOS-3 to Jason-1From GEOS-3 to Jason-1
Error budget of altimeter missionsError budget of altimeter missions
Ocean signal
0
10
20
30
40
50
60
70
80
90
Orbit error
Alt. Instr. error
Ionosphere
Troposphere
EM Bias
100
Centimeters
GEOS 3 SEASAT GEOSAT ERSI T/P(before launch)
T/P(after launch)
Jason-1(before launch)
12WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
TOPEX/POSEIDON RESULTS
13WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
TOPEX/POSEIDON - JASON Achievements
14WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
MAIN RESULTS
• Rise of the mean sea level of about 3 cm within 10 years according to TOPEX-POSEIDON
• Complex interaction between the oceans and the atmosphere. An example is El Niño event: warm waters are pushed to the West coast of South America, disrupting normal winter conditions throughout the Pacific ocean. Reliable predictions of El Niño occurrence will lead to better preparation for its widespread impact.
15WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
El Niño/La Niña as seen by TOPEX/Poséidon (NASA/CNES)
16WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
17WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
18WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
MERCATOR :Towards an integrated, multi-parameter approach of
ocean modelling and operational forecasting
19WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
OCEAN MODELLING & FORECASTING
OCEAN : turbulent & chaotic medium
Integrated approach necessary with :– Space based observations– in situ measurements– numerical models– multi-data analysis & assimilation
French initiative : MERCATORProcess similar to weather forecast
.
20WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
The MERCATOR mission was defined in 1996 by six partner organizations. The project is pursuing three goals:
• Develop an operational oceanography system
• Develop downstream oceanography applications
Mercator Users :
• « Sea people »
• « Science people »
• « Climate people »
• « Coastal people »
21WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Mercator, towards operational oceanography
2002
2003
2004
1/3°
1/15°
2°
1/4°
1/15°
Modelisation & Assimilation
Observation : Satellite & In situ
22WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
MERCATOR OBJECTIVES
• For its scientific users, MERCATOR is an operational ocean observatory: by systematically combining, over several years, all the information yielded from observations (measurements reflecting reality) with that provided by the model (a three-dimensional view and a memory of past states), it can produce a view of the ocean that is continuous in both space and time. This integrated view is extremely valuable, as it exists nowhere else. It provides a reference state which can be examined or enhanced … as well as the raw materials to do it.
• For the ocean, MERCATOR provides information of salinity, state of surface down to 1000 m of depth thanks to the satellite and to the in situ data. The forecast are valid for 2 weeks.
23WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
MERCATOR system
CORIOLIS
TOPEX, JASON, ...
24WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Altimetry & Oceanography - Operational Organization
Altimetry missions :Jason, ENVISAT,
DORIS/SPOT
Other space data (temperature, salinity,
colour)
In situ Data: ARGO, CORIOLIS
Assimilation, forecast :
MERCATOR
Value-addedProducts
Users
Research
25WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
26WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
OCEANOGRAPHY APPLICATIONS
Research"Interesting structures to study"
Fishing"Find fish"
Routing"Find the most economical route"
Navy"See without being seen"
27WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
Fisheries
• need to understand, model and predict the effects of ocean conditions on fish populations
• can help locate areas with a higher probability of finding fish and reduce search time and operation costs
• description of the upper ocean at high space and time resolution needed
• start to use external information (e.g. SST, ocean colour, altimetry).
• a global and integrated approach should allow the development of improved products for fisheries and a better management of stocks
Altimeter product from T/P and ERS-2 for fisheries in the Indian ocean
28WMO Workshop, Geneva - March 20-21, 2006 J. PLA - CNES
MERCATOR : future activities
The MERCATOR mission seeks to develop and deploy a truly operational oceanography system over the next five years capable of analyzing and predicting ocean conditions around the globe : the Centre for Operational Oceanography (C2O)
This system will describe and predict ocean conditions over the whole ocean column continuously and in real time, at scales ranging from global phenomena to regional areas.