The Louvain-la-Neuve sea ice model : current status and ongoing developments

T. Fichefet, Y. Aksenov, S. Bouillon, A. de Montety, L. Girard, H. Goosse, C. König, O. Lecomte,

O. Lietaer, G. Madec, F. Massonnet, P. Mathiot,M.A. Morales Maqueda, M. Vancoppenolle and J. Weiss

Sea ice dynamics

Elastic-viscous-plastic (EVP) rheology on a C-grid

Transport of snow/iceproperties

C-grid, numerical method that conserves the second-order moments of the advected quantity

Sea ice mechanical redistribution

Redistribution functions that take into account ridging and rafting processes as well as ridge porosity

• Energy conserving thermodynamic model with 1 snow layer and 5 ice layers (effect of brine pockets on ice thermal properties explictly accounted for)

• Surface albedo parameterised as a function of surface state, snow and ice thicknesses, and cloudiness

• Snow ice formation scheme

• Transport in thickness space : linear remapping

Sea ice halo-thermodynamics

Sea ice age

Prognostic equation for sea ice age

LIM3, a 5-category sea ice thickness, enthalpy, salinity and age distribution model

• Bulk sea ice salinity calculated by taking into consideration brine entrapment during freezing and the most important brine drainage mechansims

• Vertical salinity profile parameterised as a function of bulk salinity and ice thickness

• Parameterisation of frazil ice production in open water areas

ForcingNCEP/NCAR daily surface air temperatures and wind speeds (1948-2006)

+ monthly climatological surface relative humidities, cloud fractions and precipitation rates + monthly climatological river runoffs

Bulk formulasSurface fluxes of heat, freshwater and momentum (no salinity restoring)

Tripolar global grid, 2° resolution

LIM3 (sea ice model)

• Explicit representation of the subgrid-scale ice thickness, enthalpy, salinity and age distributions (5 categories)

• Multi-layer halo-thermodynamic component (1 snow layer + 5 ice layers)

• Mechanical redistribution that takes into account ridging/rafting processes and ridge porosity

• EVP rheology on a C-grid

NEMO (ocean model)

• Primitive equation, free surface ocean general circulation model on a C-grid

• Level-1.5 turbulence closure scheme

• Isopycnal mixing + G&M parameterisation of eddy- induced tracer advection

• Bottom boundary layer scheme + partial step topography, L31

NEMO-LIM3 and its forcing

Sea ice concentrations averaged over 1979-2004

Comiso (2007)

September sea ice concentrations averaged over 1979-2004

OBS = Comiso (2007)

Time series of monthly sea ice area anomaly

NH : correlation = 0.74 ; SH : correlation : 0.65.

ModelComiso (2007)

Bulk sea ice salinities averaged over 1979-2006 (in psu)

March

March

Sept.

Sept.

Annual maximum mixed layer depths averaged over 1979-2006 (in m)

OBS = de Boyer Montégut et al. (2004)

Impact of a prognostic sea ice salinity on the annual mean ice thickness (left) and sea surface salinity (right)

CTRL BK5 CTRL BK5

∆ ice thickness (m) ∆ sea surface salinity (psu)

CTRL = control run ; BK5 : run with a prescribed sea ice salinity of 5 psu.

Impact of a prognostic sea ice salinity on the annual mean ice thickness (left) and sea surface salinity (right)

CTRL BK5 CTRL BK5

∆ ice thickness (m) ∆ sea surface salinity (psu)

CTRL = control run ; BK5 : run with a prescribed sea ice salinity of 5 psu.

Vancoppenolle, M., T. Fichefet and H. Goosse, 2009 : Simulating the mass balance and salinity of Arctic and Antarctic sea ice. 2. Sensitivity to salinity processes. Ocean Modell., 27, 54-69.

Vancoppenolle, M., T. Fichefet, H. Goosse, S. Bouillon, G. Madec and M.A. Morales Maqueda, 2009 : Simulating the mass balance and salinity of Arctic and Antarctic sea ice. 1. Model description and validation. Ocean Modell., 27, 33-53 ;

For further details, see

• Implementation in LIM3 of a data assimilation scheme based on an ensemble Kalman filter approach (done ; tests under way by means of twin experiments).

• Inclusion in NEMO-LIM3 of the re-scaled vertical coordinate z* proposed by Campin et al. [2008] (done ; validation under way).

• Development of a parameterisation of ice growth in pancake fields for incorporation into LIM3 (under way).

Ongoing developments

• Development and inclusion in LIM3 of a comprehensive snow model (1D version nearly ready).

• Development of a new sea ice rheology formulation based on a progressive damage model (under way).

Progressive stress loading

Fixed boundary

Entirely damaged

Damage levelat the end of a stress loadingUndamaged

[Girard et al., JSTAT, submitted]

• Coupling of LIM3 with a sea ice biogeochemistry module (1D version validated ; extension to 3D in progress).

Example of simulation of the seasonal cycle of temperature, brine volume and algae concentration in Antarctic sea ice

[Vancoppenolle et al., JGR, in press]

• Development of a finite element (FE) version of LIM3 (FE version of LIM2 in both Eulerian and Lagrangian formulations validated on a cartesian grid ; introduction of spherical geometry completed ; inclusion of LIM3 physics in progress ; coupling with the LLN FE ocean model planned).

www.climate.be/slim

[Lietaer et al., Ocean Modell., 2008]

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