The North Atlantic and Mediterranean Sea Prototype (PSY2V3 : Prototype SYstem 2 Version 3) has been carried out by Mercator Ocean Team (Toulouse, France) in the framework of the High Resolution Atlantic Forecasting System. It is operational since April 2008. This system includes the IBI area and can provide initial and boundary conditions for the subregional and coastal systems of this area. The domain spreads from 20°S to 80°N and embeds the IBI area (20°W ' 0° and 30°N' 52°N). PSY2V3 has a 1/12° horizontal resolution (3-9 km) with 50 z-levels (from 1m near the surface to 400m at the bottom). This finite difference model is based on OPA calculation code (Madec, Delecluse et al., 1999) which resolves primitive equations. PSY2V3 is initialized from a stable state using as input , temperature and salinity conditions taken from Reynaud et al., (1998) climatology in the Atlantic and MEDATLAS (2002) in the Mediterranean Sea.
Concerning the boundary conditions :

• The Northern and Southern boundaries are buffer zones with a relaxation of the temperature and salinity towards Reynaud and MEDATLAS climatologies;
• The ocean-earth friction is a partial slip condition for the lateral friction and non linear bottom boundary friction;
• The atmospheric forcing is the daily operational ECMWF wind stress, precipitation and evaporation, total cloud cover, 2m air temperature, 2m air humidity and 10m wind. The surface heat fluxes are recalculated by the ocean model following the bulk formulae CLIO (Oberhuber, 1988). 24 river runoffs are taken into account in the evaporation minus precipitation term.

The assimilation method (named SAM2V1) is based on Multivariate Multidata Optimal algorithm and uses 2D analytical (horizontal) + 1D (vertical) EOFs to extract. The assimilated data are : the altimetric SLA (Jason-1, Envisat, GFO), the SST Reynolds and the in situ T/S vertical profiles.

Each Wednesday, forecasting system is run in order to produce analysis and forecats.
28 dates are produced : 14 analysis and 14 forecasts.
Analysis are 7 Hindcasts from D-14 to D-8 and 7 Nowcasts form D-7 to D-1.

The following scheme descibes the weekly production sequency :

• ocean mixed layer thickness
• sea ice area fraction
• sea ice thickness
• zonal sea ice velocity
• meridian sea ice velocity
• sea surface height above geoid
• surface downward heat flux in sea water
• zonal surface downward stress
• meridian surface downward stress
• surface net downward shortwave flux
• water flux into ocean

• Zonal velocity (currents)
• Meridian velocity (currents)
• Vertical velocity (currents)
• Salinity
• Potential Temperature

The data file products at Mercator are available in standard regular grid in Mercator projection. File format is NetCDF following COARDS/CF 1.0 convention.

There are 2 kinds of data :

1/ 1/6° products in all North Atlantic ocean (1/8° for the Mediterranean Sea)

2/ Full resolution 1/12° products in IBI domain (Iberia-Biscay-Ireland)

Each kind of data are available on its own OpenDAP (i.e. : for PSY2V3 or for IBI)

To access these products, you can find all the details on the “Products” section in our web site http://www.mercator.eu.org/.

Forecast data are granted free of charge for research and public institute, you just have to fill a form that you can download on our web site http://www.mercator.eu.org/.

Product is validated immediately after production by comparing outputs to observations (insitu, altimetry, sst, …).
A validation on time series is also carried out all along the forecasting system lifetime.