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A Regional Ice-Ocean Simulation Of the Barents and Kara Seas W. Paul Budgell

IMR. A Regional Ice-Ocean Simulation Of the Barents and Kara Seas W. Paul Budgell Institute of Marine Research and Bjerknes Centre for Climate Research Bergen, Norway ROMS User Meeting, Venice October 18-21, 2004. IMR. Outline of Talk : Background Description of ice-ocean model

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A Regional Ice-Ocean Simulation Of the Barents and Kara Seas W. Paul Budgell

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  1. IMR A Regional Ice-Ocean Simulation Of the Barents and Kara Seas W. Paul Budgell Institute of Marine Research and Bjerknes Centre for Climate Research Bergen, Norway ROMS User Meeting, Venice October 18-21, 2004

  2. IMR • Outline of Talk: • Background • Description of ice-ocean model • Model set-up • Simulation results • Comparison with observations

  3. IMR • Background • Region of interest is the Barents Sea • Dynamical downscaling experiments • First replicate present-day climate • Validate with available observations

  4. IMR Model Domain

  5. IMR • Ocean Model Component • Community Regional Ocean Modelling • System (ROMS) version 2.1 • Terrain-following coordinate system with • generalized vertical coordinate, • curvilinear coordinates in horizontal • Wide variety of mixing schemes available • Advanced numerics, OMP and MPI parallel.

  6. IMR • Ocean Model Component • Used 3rd-order upwind-biased horizontal advection • Used piece-wise parabolic splines in vertical, • spline vertical advection, spline Jacobian baroclinic • pressure gradient at topography • Used GLS mixing with MY2.5 parameters • No explicit horizontal viscosity or diffusivity

  7. 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 to viscous-plastic models in typical Arctic pack ice conditions. Numerical behaviour improved significantly by applying linearization of the viscosities at every EVP time step. The EVP model parallelizes very efficiently under both OpenMP And MPI.

  8. IMR • Ice Thermodynamics • Ice thermodynamics are based upon those of Mellor and • Kantha (1989) and Häkkinen and Mellor (1992). Main features • include: • 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

  9. Model Set-up IMR

  10. IMR • Model Set-up • Horizontal resolution of 7.8 to 10.5 km, • average of 9.3 km • 32 levels in the vertical • Flather (free surface) and Chapman • (momentum) open boundary • conditions for 2D variables • Nudging + radiation condition OBCs • for 3D-mom and tracers

  11. IMR • Boundary and Initial Conditions • Tidal forcing from AOTIM • Coarse model used for initialization and • boundary forcing of regional model • 50 km resolution in Nordic Seas/Arctic • NCEP daily mean fluxes (Bentsen and • Drange, 2001) used for forcing • Hindcast from 1948-2002 completed, • archived 5-day mean fields

  12. IMR

  13. IMR

  14. IMR Results are shown from the first year of a1990-2002 simulation SSTIce Concentration

  15. IMR Comparison with observations: SST from PODAAC Pathfinder AVHRR best SST, ascending (day-time) orbit, 8-day, 9-km means Ice concentration from SSM/I passive micowave, daily means Bjørnøya-Fugløya CTD sections

  16. IMR SST

  17. IMR Sea Ice Concentration

  18. IMR Section Locations

  19. T - Bjørnøya-Fugløya Section - March IMR

  20. T - Bjørnøya-Fugløya Section – Sept. IMR

  21. S - Bjørnøya-Fugløya Section – Sept. IMR

  22. Brine Drainage Spitzbergen Section IMR

  23. Brine Drainage W. Novoya Zemlya Section IMR

  24. Ice Production - 1993 IMR

  25. Ice Melt - 1993 IMR

  26. IMR • Conclusions • Model captures seasonal variability in the Barents • Good agreement with observed ice distribution • Barents inflow is too cold, too fresh – OBC issue • Brine rejection from ice formation produces realistic water • masses • ROMS captures significant portion of mesoscale variability • even with 9-km resolution

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