Mercator Ocean International

Mercator Ocean International (MOi) is an intergovernmental organisation, providing ocean science-based services of general interest focused on the conservation and the sustainable use of the oceans, seas and marine resources.

The organisation

The organisation was originally  founded and funded by the five major French institutions involved in operational oceanography: CNRS (National Center of Scientific Research), Ifremer (French Research Institute for Exploitation of the Sea), IRD (Institute of Research for Development), Météo-France and SHOM(Hydrographic and Oceanographic Service of the French Navy.  In December 2017, they decided to open up the capital of Mercator Ocean to major and prominent players in operational oceanography to strengthen Mercator Ocean’s capacity to expand in Europe and internationally. They are major national players in operational oceanography worldwide and key scientific partners of the Copernicus Marine Service and they now include: the Italians CMCC (Centro Euro-Mediterraneo sui Cambiamenti Climatici) and CNR (Consiglio Nazionale delle Ricerche), the Norwegian NERSC (Nansen Environmental and Remote Sensing Center), the British MET OFFICE, and the Spanish Puertos Del Estado. At the One Ocean Summit organised by France in Brest in February 2022, six European states (France, Italy, Norway, Portugal, Spain, and the UK) showed commitment to developing European oceanographic excellence by transforming MOI into an intergovernmental body through the “Brest Declaration”.

MOi has developed complex ocean simulation systems (numerical models) based on ocean observation data (satellite and in situ) that are able to describe, analyse and forecast the physical and biogeochemical state of the ocean at any given time, at the surface or at depth, on a global scale or for a specific zone, in real-time or delayed mode.

As an entrusted entity 

After running the European MyOcean projects since 2009, Mercator Ocean was officially appointed by the European Commission on November 11th, 2014 to implement the European ocean-monitoring service, the Copernicus Marine Service (CMEMS),  as part of the European Earth observation programme, Copernicus. It is an unprecedented service, free, and open to all, accessible via a web portal that now serves about 30 000 intermediate users around the world. Having sufficient knowledge to be able to describe and forecast, among other ocean parameters, temperature, currents, salinity, the thickness of sea ice in all the oceans of the world, above and below the surface, but also their oxygen content, pH, nutrients and plankton gives the world a decisive operational capacity for scientific research, the protection of citizens and for the sustainable management of the ocean and development of the blue economy (marine energy, safety at sea and maritime routing, fishery and aquaculture management, etc). This delegation agreement covers EUR 147 million from 2014 to 2021.

MOi is also in charge together with EUMETSAT, ECMWF and the European Environment Agency (EEA) of the implementation of the WEkEO DIAS cloud computing platform. And MOi also brings its expertise in a new frontier of international ocean governance by coordinating the EU4OceanObs project.

Our Director General, Pierre Bahurel is the Chair of ETOOFS (Expert Team on Operational Oceanography and Forecasting Systems) which is an international group of GOOS (Global Ocean Observing System) and IOC-UNESCO. It works to create standards and best-practices for operational oceanography and to democratise this information and knowledge for global use.

Operational systems descriptions

Mercator operates its first system in 2001, based on OPA ocean model (OPA is now the “blue” component of NEMO). Now, Mercator Ocean operates global forecasting systems and produces global and regional reanalysis, all based on NEMO ocean model, coupled to a data assimilation system:

Interests in NEMO OGCM

In order to improve the operational systems, Mercator’s ocean modellers are working on several aspects of the NEMO model:


Improvement of the vertical physics: vertical mixing parametrization, light penetration scheme, ocean/waves interaction;

Improvement of the surface boundary condition: development of an Atmospheric Boundary Layer (space and time downscaling of the atmospheric forcing ) and upgrade of Sea ice to the multi category LIM3 sea ice model;

Tide forcing: the tide is already used in regional reanalysis and operational forecasting system, main objective is now to improve configuration including tide and to move to global configuration for short term forecast but also for long inter-annual reanalysis;


Horizontal coordinate: increase the resolution of the global and regional forecasting system: at global scale an operational system at ~2 km resolution could be envisaged and at regional scale the resolution could be less than 1km.

Vertical coordinate: Using a z~ ALE vertical coordinates could reduce spurious numerical mixing and using a generalized vertical coordinate could improve water masses representation;

Numerical schemes: To use NEMO model at higher resolutions, higher order advection scheme are needed, with a limited CPU cost;

AGRIF is the two-way nesting tool available in NEMO, it has been developed since several years and is currently used for R&D activities, to test and validate some numerical approaches. It will be used to define the next version of the global high resolution operational forecasting system, especially to define precisely the optimal resolution and the numerical schemes adapted to this resolution. The option consisting in AGRIF zooms in strategic areas in a global configuration will be also investigate.;

Ensemble approach

The ensemble approach is essential in operational oceanography to move to an ensemble data assimilation method which will allow a much better representation of the error covariances and to move from a deterministic to an ensemble forecast. NEMO already includes stochastic parametrization, perturbation method and technical solution to perform ensemble simulation. The huge numerical coast and the huge quantity of model output generated by such method will imply new development to optimize the method to perturb the model and to optimize the IO library.