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Coupling of the met.no ice model to MICOM

Coupling of the met.no ice model to MICOM. Jens Debernard Presented at LOM-meeting , 2 6 .-2 8 .1.200 5 , Miami. Coupling of the met.no ice model to MICOM and MIPOM. Jens Debernard Presented at LOM-meeting , 2 6 .-2 8 .1.200 5 , Miami. Overview. The sea ice model MI-IM

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Coupling of the met.no ice model to MICOM

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  1. Coupling of the met.no ice model to MICOM Jens Debernard Presented at LOM-meeting, 26.-28.1.2005, Miami

  2. Coupling of the met.no ice model to MICOM and MIPOM Jens Debernard Presented at LOM-meeting, 26.-28.1.2005, Miami

  3. Overview • The sea ice model MI-IM • Differences when coupling with MICOM or MIPOM • Inertial oscillations • Some results from a regional coupled atmosphere and ocean system. • Summary

  4. The met.no ice model MI-IM • 3-layer Semtner-type model • Prognostic equations for: ice volume, snow volume, ice concentration, internal heat of the ice • EVP dynamics • Positive definite advection (non-oscillatory MPDATA) • Discretized at C-grid • Soon: MPI-parallelized

  5. The met.no ice model MI-IM • 3-layer Semtner-type model • Prognostic equations for: ice volume, snow volume, ice concentration, internal heat of the ice • EVP dynamics • Positive definite advection (non-oscillatory MPDATA) • Discretized at C-grid • Soon: MPI-parallelized

  6. Conservation of mass Ice volume Snow volume Ice area (concentration) H(x) = 0, x< 0 and H(x) = 1, x> 0

  7. Qai Qao Qoa Qoi Sea ice as a heat reservoir between the atmosphere and the ocean A - Ice concentration h – Ice thickness

  8. MI-IM coupled to the ocean models: • MICOM • MIPOM Or MI-POM (the met.no version of the POM)

  9. MICOM vs MIPOM

  10. Thermodynamical coupling, 1 • MICOM: Omstedt & Wettlaufer, JGR, 1992 Qoi = rOcpw cht|Vi-Vo|(TO – Tf), Tf = mSio, cht=2x10-4 • MIPOM: Mellor & Kantha, JGR, 1989 Qoi = rOcpw ctZ(TO – Tf) ctz = u*/[Prtk-1ln(z/z0)+b (z0u*/n)1/2Pr2/3] Prt = 0.85, Pr = 12.9, b = 3.14

  11. Thermodynamical coupling, 2 • MICOM: Omstedt & Wettlaufer, JGR, 1992 Qoi = rOcpw cht|Vi-Vo|(TO – Tf), Tf = mSio Fs = [u*/(3.0 Sc)] (S0 – Sio) Sc = 2432 • MIPOM: Mellor & Kantha, JGR, 1989 Qoi = rOcpw ctZ(TO – Tf) ctz = u*/[Prtk-1ln(z/z0)+b (z0u*/n)1/2Pr2/3] Prt = 0.85, Pr = 12.9, b = 3.14 FS= Csz(SO – Sio) csz = u*/[Prtk-1ln(z/z0)+b (z0u*/n)1/2Sc2/3]

  12. Dynamical coupling • MICOM: Tio = rO cdio|Vi-Vo|[ (Vi-Vo)cos() + k x (Vi-Vo) sin()] cdio ≈ 5x10-3 ,  ≈ 23º • MIPOM Tio = rO cdz |Vi-Vo| (Vi-Vo) cdz = u*/(k-1ln(z/z0))

  13. MICOM or MIPOM MI-IM FT,FS,T(x),T(y) TO,SO,UO,VO,HS,Wfrz T1 T1 FT,FS,T(x),T(y) TO,SO,UO,VO,HS,Wfrz T2 T2 Coupling time-scheme

  14. Inertial oscillations • We have experienced problems in MICOM with unstable inertial oscillations due to the stress turning term in a C-grid. • No problems for dynamical coupling time-steps > 12 h (2p/f). • MIPOM can be unstable for very thin surface sigma-layers. • Implicit calculation of ice-ocean stress inside MIPOM is required

  15. 1992 02

  16. 1993 02

  17. 1994 02

  18. 1995 02

  19. 1996 02

  20. Summary • Different vertical representation of the upper ocean is the fundamental difference between the coupling to MICOM and MIPOM. • Coupling should be easier in z-level or hybrid-layer models with a reasonable resolved, equidistant grid-spacing in the upper ocean. • Unstable inertial oscillations may occur in both types of systems but they are avoidable. • Ice models like MI-IM has to be tuned to give a realistic amount of sea ice, both in stand-alone ice-ocean simulations and when coupled to atmosphere models.

  21. END

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