In Situ Validation of Jason-1 and Jason-2 Altimetry Missions in the Tropical Atlantic Ocean

Abstract

Nearly 20 years of altimetry data provide a new tool for studying low frequency variability in the ocean. However, in the tropics, where a few centimeters of uncertainty in sea level can result in large errors in velocity, accuracy is a problem. The ARAMIS program (Altimétrie sur un Rail Atlantique et Mesures in Situ) surveyed temperature and salinity structures in the tropical Atlantic Ocean. In this work, in situ measurements are compared to Jason-1 and -2 data from 2008 in order to check the reliability of inferring tropical Atlantic Ocean dynamics from both data sets, and to validate Jason-2.

Keywords:

• Altimetry
• tropics
• Atlantic

Acknowledgements

The ARAMIS project was funded by the French CNES (Centre National d’Etudes Spatiales) and the IRD (Institut de Recherche pour le Développement) organizations. We are grateful to the U.S. IRD IMAGO, to the Hamburg Sud, to CGM/CMA crews, and to all of the participants of the ARAMIS cruise for their help.

Ssalto/Duacs altimeter products were produced by Ssalto/Duacs and distributed by Aviso, with support from Cnes (http://www.aviso.oceanobs.com/duacs/). The other altimeter products used here were produced and distributed by Aviso (http://www.aviso.oceanobs.com/), as part of the Ssalto ground processing segment. We thank the AVISO group for helpful comments regarding these data sets.

The Argo data were collected and made freely available through the International Argo Project and the national programs that contributed to the projects (http://www.argo.ucsd.edu, http://argo.jcommops.org). Argo is a pilot program of the Global Ocean Observing System. We especially thank the Argo Data Center in Brest for their advice.

São Tomé tide gauge data were downloaded from the PIRATA web site (http://www.ifremer.fr/ird/pirata/sao_tome_fr.php#tg).

Sabine Arnault and Jean-Luc Mélice are supported by IRD. Isabelle Pujol is supported by CLS.