A Coupled Ice-Ocean Model Based on ROMS/TOMS 2.0

W. Paul Budgell

Institute of Marine Researchand

Bjerknes Centre for Climate ResearchBergen, Norway

Terrain-Following ModelUser’s Group Meeting

Seattle, August 4-6, 2003

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Outline of Talk:

• Description of ice model

• Coupling of ice model to ROMS

• Basin-scale coupled ice-ocean model

• To do

IMR

Outline of Talk:

• Description of ice model

• Coupling of ice model to ROMS

• Basin-scale coupled ice-ocean model

• To do

IMR

Ice Dynamics

Ice dynamics are based upon the elastic-viscous-plastic (EVP)rheology of Hunke and Dukowicz (1997), Hunke (1991) and Hunke and Dukowicz (1992).

Under low deformation (rigid behaviour), the singularity is regularized by elastic waves. The response is very similar toviscous-plastic models in typical Arctic pack ice conditions.

Numerical behaviour improved significantly by applyinglinearization of the viscosities at every EVP time step.

The EVP model parallelizes very efficiently under both OpenMPAnd MPI.

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Ice Thermodynamics

Ice thermodynamics are based upon those of Mellor andKantha (1989) and Häkkinen and Mellor (1992). Main featuresinclude:• Three-level, single layer ice; single snow layer• Molecular sublayer under ice; Prandtl-type ice-ocean boundary layer• Surface melt ponds• Forcing by short and long-wave radiation, sensible and latent heat flux• NCEP fluxes, corrected for model surface temperature and ice concentration, used as forcing

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Outline of Talk:

• Description of ice model

• Coupling of ice model to ROMS

• Basin-scale coupled ice-ocean model

• To do

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Coupling of Ice Model to ROMS

Tried to keep things modular:

In main3d.F: ice routines NCEP flux routines

CALL ice_albedo (ng,tile) CALL cawdir_eval (ng,tile) CALL ncep_flux (ng, tile) CALL ice (ng)

CALL ice_frazil(ng,tile)

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Coupling of Ice Model to ROMS

New ice variables stored in mod_ice.F

Ice model contained in ice.F:• computes ice-ocean fluxes• performs EVP dynamics• performs advection of all ice/snow prognostic variables• performs ice/snow thermodynamics

ice_frazil.F:• checks for water masses below freezing point• computes ice growth mass flux from frazil ice formation• adjusts T and S for ice formation

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Outline of Talk:

• Description of ice model

• Coupling of ice model to ROMS

• Basin-scale coupled ice-ocean model

• To do

IMR

Transformed Spherical Grid

Surface Temperature (deg C) 1949/03/06

Sea Surface Height (m) 1949/03/06

Ice Concentration (1949/03/06)

Ice Concentration (1949/03/06)

Ice Concentration (1949/09/30)

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Simulated Sea Ice Thickness 1949

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Outline of Talk:

• Description of ice model

• Coupling of ice model to ROMS

• Basin-scale coupled ice-ocean model

• To do

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Work in Progress

• Clean up the code

• Fix small parallelization inconsistency

• Developed idealized test cases for analytical.F• ICE_BASIN• ICE_OCEAN_1D

• Modify bulk_flux.F to take ice forcing

• Implement open BC FRS scheme for ice variables (B. Ådlandsvik)

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Work in Progress/Future Work

• Implementation on a 4-km grid for the Barents region

• Run AOMIP

• Implement full metric terms for curvilinear grid (Hunke and Dukowicz, 2002)

• Multiple ice thickness categories, energy conservation (NCAR, CICE, Bitz and Lipscomb (1999))

• Couple high-resolution ice-ocean ROMS to mesoscale atmospheric model MM5 (Polar)