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ScienceInitiate's trailModellingNEATL36 Simul. | Physics | Geog. Ext.
Resol. | Oc./atm. interf. | Bound. Cond.
Input | Comput. | Oper.

ORCA2 | ORCA025 | ORCALIM025 | ORCA12 | PAM | MNATL3 | MNATL4 | MNATL12 | NEATL12 | NEATL36

1/36° Atlantic coast (NEATL36)

Existing simulations

1993-2000, forced by daily ERA40. No existing simulation yet.

Physics

Overview

NEMO (OPA9 + LIM) (Madec, Delecluse and 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)
  • No filtered free surface, time splitting
  • Tide potential.
Output data
  • Model state variables : temperature, salinity, zonal and meridian velocity, free surface elevation and vertical diffusivity coefficient
  • Atmospheric forcing: zonal and meridional wind stress, penetrating heat flux, solar flux, non solar flux, salt flux, snow flux, precipitation and runoff minus evaporation budget
  • Diagnostic variables: mixed layer depth (one density diagnostic, one vertical mixing diagnostic), sea level elevation, barotropic height, dynamic height, mass transport by density class through sections, meridional heat transport
Physical parameterizations
  • Diffusion: laplacian isopycnal operator
  • Viscosity : bilaplacian horizontal operator
  • Energy and enstrophy conserving advection scheme
  • TKE (turbulent kinetic energy) vertical mixing model
  • Partial slip lateral boundary friction condition
  • Non linear bottom friction
  • Partial step vertical coordinate
Restoring zones
    No

Geographical extension

North-East Atlantic from 26°N to 65°N and from 26°W to the European coast

Resolution

Horizontal resolution
    1/36° ORCA grid, between 1.7 and 2.7 Km. Number of points : 1081 x 1832.

    NEATL36 grid resolution (Km)
Vertical resolution
    50 levels. From 1 m at the surface to 450 m at the bottom

    NEATL36 vertical resolution (see black diamonds)

Ocean atmosphere interface

Bulk formaulation (CLIO). The monthly climatological flow of the main rivers is taken into account in the evaporation minus precipitation budget (Dai and Trenberth, 2002). A parameterization of the penetrating heat flux is used.

Ocean boundary conditions

Open boundaries at 26°N, at 26°W, at 65°N and in the Alboran Sea. Main rivers are taken into account at open boundaries.

Input data

Forcing
    ECMWF (2000-2005) daily operational analysis. Zonal and meridional wind stress components, wind module, relative humidity, cloud coverage, rain, air temperature.
Climatology
    Monthly Levitus temperature and salinity from Levitus 98.
Bathymetry
    Combination between: ETOPO2, for the open ocean, and GEBCO (IOC, 2003) for continental shelves.

Computing cost

For one year of simulation on IBM Power 4:
  • 64 Gigabytes of memory
  • 40 000 CPU hours
  • 900 Gigabytes of output (daily output)

Operational

2009