1/4° global configuration with sea ice modelling (ORCALIM025)

Existing Simulations


Turbulent kinetic energy (m2/s2) : global average 1993-2001.	North Pole: sea ice extension (%), average March 2001.	North-West Atlantic : temperature at 320m, average 1993-2001.

Physics

Overview

NEMO (OPA9 + LIM) (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)
Linearised and filtered free surface
Nested with LIM sea ice model (Timmermann et al., 2004)

Output data

Model state variables : temperature, salinity, zonal and meridian velocity, free surface elevation and vertical diffusivity coefficient
Sea ice variables: thickness ice, ice concentration, ice temperature, zonal and meridional ice velocity, snow thickness on ice, ice heat content
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 (300 m2/s)
Viscosity : bilaplacian horizontal operator (-3 E11 m2/s)
Energy and enstrophy conserving advection scheme
TVD advection scheme
TKE (turbulent kinetic energy) vertical mixing model
Partial slip lateral boundary friction condition
Non linear bottom friction
Bottom boundary layer
Partial step vertical coordinate

Restoring zones

Gibraltar Strait exit, in the Gulf of Cadiz and Bab El Mandeb Strait, in the Gulf of Aden

Résolution

Horizontal resolution


ORCA025 grid resolution (Km)

Vertical resolution

50 levels, with a discretization of 1 meter until 20 meters depth and 500 meters in the bottom layers.

Ocean atmosphere interface

Bulk formulation (CLIO). Main rivers monthly runoff and coastal runoff are taken into account in the evaporation minus precipitation budget (Dai and Trenberth, 2002). A solar flux penetration parameterization is used.

Input data

Forcing

ERA40 reanalysis (1992-2001) and ECMWF daily operational analysis (1998-2005). Zonal and meridional wind stress components, wind modulus, relative humidity, cloud coverage, precipitation, air temperature.

Climatology

Bathymetry

ORCALIM025 Bathymetry (m)

Computing cost

For one year of simulation on IBM Power 4:

47 Gigabytes of memory
3500 CPU hours
120 Gigabytes of output (daily output)

Operational

PSY3V2