Mercator Ocean runs operational services and provides expertise to a large panel of users: scientists, public authorities, agencies and even the pri-vate sector. This month’s newsletter gives a focus on four areas of benefits. First article is dedicated to the contribution of Météo-France and Merca-tor Ocean to the research at sea of the wreckage from the Air France AF447 flight from Rio to Paris. Second article presents the contribution of Mer-cator Ocean and Laboratoire d’Aerologie in order to investigate the dispersion in seawater of radionuclides after the castrophic event of the Fuku-shima nuclear plant. Third article displays the work done at Mercator Ocean in order to assist Meteo France in predicting the fate of sea pollutions or drifting objects during disasters like oil spills for example. Last article is about the Mercator Ocean state of the art reanalysis product GLORYS2V1 which is of great interest for the climate community.

On the night of June 1st to June 2nd 2009 at 2h10 GMT, the Air France AF447 flight from Rio to Paris disappeared in a highly variable and poorly observed part of the western tropical Atlantic Ocean. The two first phases of research at sea of the AF447 wreckage were both unsuccessful. The “Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile” (BEA) (for the investigation of airplane accidents) decided in November 2009 to gather a group of ocean scientists and mathematicians in order to prepare the third phase of research. The study performed by Mercator Océan and Météo-France as part of this group is partly described here with a focus on the modelling part of the common contribution of Météo-France and Mercator Ocean as an attempt to improve the currents and winds and consequently the drift accuracy.

After the castrophic event of the Fukushima nuclear plant in March 11 2011, various simulations using the 3D SIROCCO circulation model were per-formed in order to investigate the dispersion in seawater of radionuclides emitted by the Fukushima nuclear plant. In this framework, Mercator Ocean has provided the initial fields and the lateral open boundary conditions from the global 1/12° system. Moreover, for the MyOcean compo-nent of GMES, Mercator Ocean has also calculated the Lagrangian drift of water particles from the global 1/12° ocean system and has set up a week-ly web bulletin of the situation of currents published during one year from the date of the disaster.

Predicting the fate of sea pollutions or drifting objects is a crucial need during disasters. In case of incident over the French marine territory, Météo France has the responsibility to provide reliable ocean drift forecasts for authorities and decision makers using the oil spill model MOTHY which is operated on duty 24/7/365. Since 2007, MOTHY is fed with currents forecasted by Mercator Ocean’s assimilated systems. Stephane Law Chune et al. presents their work using the Mercator Ocean velocity fields in order to provide better current forecast to Météo France. This cooperation al-ready provided helpful assistance in the past, like during the Prestige incident (10 years ago).

The fourth paper presents the Mercator ocean GLORYS2V1 (1993-2009) global ocean and sea-ice eddy permitting reanalysis over the altimetric era. Main improvements with respect to the previous stream GLORYS1V1 (2002-2009) are shown. Data assimilation diagnostics reveal that the reanalysis is stable all along the time period, with however an improved skill when Argo observation network establishes. GLORYS2V1 captures well climate signals and trends and describes meso-scale variability in a realistic manner.

The next April 2012 issue will be a special publication with a common newsletter between the Mercator Ocean Forecasting Center in Toulouse and the Coriolis Infrastructure in Brest, more focused on observations.

We wish you a pleasant reading!

•  Meteo-France and Mercator Ocean contribution to the search of the AF447 wreckage
• Mercator Ocean operational global ocean system 1/12° PSY4V1: performances and applications in the context of the nuclear disaster of Fukushima
• Drift forecast with Mercator Ocean velocity fields and addition of external wind/wave contribution
• GLORYS2V1 Global ocean reanalysis of the altimetric era (1993-2009) at meso scale