Atlantic and Mediteranean configuration at 1/12°(MNATL12)

Existing Simulations

atl12_ssh

Sea surface height (cm)

 		2000-2005 forced by operational analysis ECMWF

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)
  •  Linearised and filtered free surface
  •  Nested with LIM sea ice model.

Output data

  • Model state variables : temperature, salinity, zonal and meridian velocity, free surface elevation and vertical diffusivity coefficient
  • Sea ice variables: thickness ice, ice production, ice concentration, ice temperature, ice/sea interface flux, zonal and meridional ice velocity
  • 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 (density diagnostic), mass transport by density class through sections, meridional heat transport.

Physical parameterizations

  • Diffusion: laplacian isopycnal operator (100 m2/s)
  • Viscosity : bilaplacian horizontal operator (-1 E10 m2/s)
  • 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

Geographic extension

North Atlantic from 20°S to 80°N and Mediteranean sea.

Resolution

Horizontal resolution

ORCA 1/12° over all the domain, from 3 to 10 km. Number of points: 1608 x 1551.
 
Vertical resolution

From 1 m at the surface to 450 m at the bottom.
grille_mnatl12

Resolution (km) of MNATL12 grid
depth_mnatl12

Vertical resolution in MNATL12 (see black diamonds)

Ocean atmosphere interface

Bulk formulation (CLIO). The monthly climatological flow of the main rivers is taken into account in the evaporation

Ocean boundary conditions

South boundary at 20°S and North boundary at 80°N: Buffer zone where temperature and salinity are relaxed towards Levitus climatology (relaxation coefficients are between 3 and 100 days).

 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 BathymetryCombination between: ETOPO2, for the open ocean, BEDMAP (Lythe and al., 2001), for the Antarctic and GEBCO (IOC, 2003) for continental shelves.

Computing costs

For one year of simulation on IBM Power 4:
 

  • 72 Gigabytes of memory
  • 7200 CPU hours
  • 300 Gigabytes of output (daily output).

Operational

PSY2V4