CLIPPERTON campaign on altimetry side: Ocean observation site exploration
Gwenaele Jan(1) , Isabelle Bry(2) , Stéphane Calmant(3) , Laurent Testut(4) , Pascal Bonnefond(5) , and Yves Ménard(6)
2 avenue de l'europe,
(2) ENSIETA, 2, rue François Verny, 29 806 Brest cedex 9, France
(3) IRD/LEGOS, 18 avenue Edouard Belin, 31055 Toulouse, France
(4) CNRS/ LEGOS, 18 av. Edouard Belin, 31055, Toulouse, France
(5) OCA/ GEMINI, av. N. Copernic, 06130 Grasse, France
(6) CNES, 18, av. Edouard Belin, 31055, Toulouse, France
CLIPPERTON campaign on altimeters side: Ocean observation site exploration
Author : G.Jan, NOVELTIS, 2 avenue de l’Europe, F-31520 Ramonville Saint Agne
Isabelle Bry, ENSIETA, F- Brest
S. Calmant, IRD/LEGOS, 18 avenue Edouard Belin, F-31055 Toulouse
Yves Ménard, CNES, 18 avenue Edouard Belin, F-31055, Toulouse
L.Testut, CNRS/LEGOS, 18 avenue Edouard Belin, F-31055, Toulouse
P. Bonnefond, OCA/ GEMINI, avenue N. Copernic, F-06130 Grasse
Clipperton Island is a French uninhabited atoll located west of Mexico [10.2 °N; 109.3°W]. It is under wet tropical atmospheric conditions, on cyclones and tropical tempests tracks in Northeast Pacific Ocean. It’s a perturbed area both in a meteorology and geophysics view (fault and volcano chain). Ocean circulation is under El Nino influence with Kelvin waves and hot water masses going from East to West. High sea surface level departures have been detected both by altimeters and tide gauges during the Clipperton mission (10 to 25 cm).
Clipperton is over flight by 3 satellites -namely JASON, ENVISAT, GFO- that is fruitful in term of multi satellites comparisons. Using tools developed at CNES and LEGOS, we conduct an assessment of this potential new site: We have analysed the data collected in-situ by tide gauges and GPS buoys between 2005/01 and 2005/03 together with radar altimeter measurements in scope of the capability of the site for more consequent calibration campaign and oceanography research.
Comparison between tide gauges and altimeters sea level anomalies is a validity test for both measurements. We show that the tide gauge is accurate enough to detect sea level anomalies linked to the local ocean dynamics. Their optimal cross use gives a good way to characterise strong events (ex El Nino, tropical tempest, and tectonic movements)
Possibilities offered by this site have been screened keeping two objectives: altimeter calibration and ocean signal studies.