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ORCA2 |
ORCA025 |
ORCALIM025 |
ORCA12 |
PAM |
MNATL3 |
MNATL4 |
MNATL12 |
NEATL12 |
NEATL36
1/4° global configuration (ORCA025)
1992-2002 forced by daily ERA40 :
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Turbulent kinetic energy (m2/s2) in 1998 |
Sea level, 10 years average (m), in the Kuro Shio area, North Pacific |
Surface current, 10 years average |
SST (Hovmuller) between 1992 et 2002, at the Equator |
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Overview OPA8.2 (Madec, Delecluse et al. 1998), The formulation is based on so-called 'primitive' equations. These equations are derived from Navier-Stokes equations in a stratified fluid with following approximations:
- Earth's sphericity: local gravity directed towards the centre of the Earth
- Relatively shallow water: ocean depth small in relation to the Earth's radius
- Hydrostatic: equilibrium between the vertical pressure gradiant and the floatability
- Boussinesq values: variations in density are not taken into account apart from their contribution to floatability
- Incompressibility: the three-dimensional divergence of the velocity field is considered to be nil
- 1.5 order closure turbulence scheme
- Non-linear equation of state couples the two active trace indices (temperature and salinity)
- Free surface
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Output data - Model state variables : temperature, salinity, zonal and meridian velocity, barotropic stream function and vertical diffusivity coefficient
- Atmospheric forcing: zonal and meridional wind stress, penetrating heat flux, solar flux, retroaction term, precipitation and runoff minus evaporation budget, surface salinity restoring term
- Diagnostic Variables : mixed layer depth (two density diagnostic, one vertical mixing diagnostic), sea level rise, barotropic height, dynamic height, mass transport by density class through sections, meridional heat transport.
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Physical parameterization - Diffusion: laplacian isopycnal operator (500 m2/s)
- Viscosity : bilaplacian horizontal operator (-1.5 E11 m2/s) with laplacian operator (1000 m2/s) on the Equatorial band [1°N;-3°N] )
- Energy and enstrophy conserving advection scheme
- TKE (turbulent kinetic energy) vertical mixing model
- Partial slip lateral boundary friction condition
- Non linear bottom friction
- Bottom boundary layer
- Z vertical coordinates
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Restoring zones Restoring towards the Levitus climatology (T,S) at the Gibraltar Strait exit, in the Gulf of Cadiz. This restoring increases from 200 m to 400 m, then remains constant to the bottom. Another restoring towards the Levitus climatology at the Bab El Mandeb Strait, in the Gulf of Aden. This last one increases between 200 m and 400 metres, then remains constant to the bottom. |
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Horizontal resolution
ORCA grid (Arakawa type C), from 26 km at the Equator to 6 km near the poles. Number of points : 1442 x 1021.
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ORCA025 grid (Km) resolution |
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Vertical resolution
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Flux formulation with retroaction between model temperature surface and atmosphere computed from Reynolds SST (40 W/m2) and equivalent restoring towards the climatologic surface salinity (Barnier, Siefridt et al. 1995). The monthly climatological runoff of 120 main rivers is taken into account in the evaporation minus precipitation budget.
A parameterization of the penetrating solar flux is used.
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Forcing ERA40 (1992-2002).
Zonal and meridional wind stress components, solar flux , total heat flux (solar + infrared + sensitive + latent), evaporation, precipitation.
Climatology Temperature and climatological monthly salinity from Levitus 98 on the whole globe, except for Arctic where PHC climatolgy is considered and in Mediterranean where Medatlas is considered
Bathymetry Combination between ETOPO2 and BEDMAP, 2001, for high South latitudes.
 ORCA025 Bathymetry (m) |
For one year of simulation on IBM Power 4:
- 42 Gigabytes of memory
- 4000 CPU hours
- 120 Gigabytes of output (daily output)
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Beginner's trail
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