coupling of the met.no ice model to micom
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
Norwegian Meteorological Institute met.no
Coupling of the met.no ice model to MICOM
Jens Debernard
Presented at LOM-meeting, 26.-28.1.2005, Miami
Norwegian Meteorological Institute met.no
Coupling of the met.no ice model to MICOM and MIPOM
Jens Debernard
Presented at LOM-meeting, 26.-28.1.2005, Miami
Norwegian Meteorological Institute met.no
Overview
1. The sea ice model MI-IM2. Differences when coupling with
MICOM or MIPOM3. Inertial oscillations4. Some results from a regional
coupled atmosphere and ocean system.
5. Summary
Norwegian Meteorological Institute met.no
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
Norwegian Meteorological Institute met.no
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
Norwegian Meteorological Institute met.no
Conservation of mass•Ice volume
•Snow volume
•Ice area (concentration)
H(x) = 0, x < 0 and H(x) = 1, x > 0
Norwegian Meteorological Institute met.no
Sea ice as a heat reservoir between the atmosphere and the ocean
A - Ice concentrationh – Ice thickness
Qoi
Qai
Qoa
Qao
Norwegian Meteorological Institute met.no
MI-IM coupled to the ocean models:
• MICOM• MIPOM Or MI-POM
(the met.no version of the POM)
Norwegian Meteorological Institute met.no
MICOM vs MIPOM
Norwegian Meteorological Institute met.no
Thermodynamical coupling, 1
• MICOM: Omstedt & Wettlaufer, JGR, 1992
Qoi = Ocpw cht|VVii-Vo|(TO – Tf), Tf = mSio, cht=2x10-4
• MIPOM: Mellor & Kantha, JGR, 1989
Qoi = Ocpw ctZ(TO – Tf)
ctz = u*/[Prt -1ln(z/z0)+b (z0u*/)1/2 Pr2/3]Prt = 0.85, Pr = 12.9, b = 3.14
Norwegian Meteorological Institute met.no
Thermodynamical coupling, 2
• MICOM: Omstedt & Wettlaufer, JGR, 1992
Qoi = Ocpw cht|VVii-Vo|(TO – Tf), Tf = mSio
Fs = [u*/(3.0 Sc)] (S0 – Sio)Sc = 2432
• MIPOM: Mellor & Kantha, JGR, 1989
Qoi = Ocpw ctZ(TO – Tf)
ctz = u*/[Prt -1ln(z/z0)+b (z0u*/)1/2 Pr2/3] Prt = 0.85, Pr = 12.9, b = 3.14
FS = Csz(SO – Sio)
csz = u*/[Prt -1ln(z/z0)+b (z0u*/)1/2 Sc2/3]
Norwegian Meteorological Institute met.no
Dynamical coupling
• MICOM: Tio = O cdio|Vi-Vo|[ (Vi-Vo)cos() + k x (Vi-Vo) sin()]
cdio ≈ 5x10-3 , ≈ 23º
• MIPOMTio = O cdz |Vi-Vo| (Vi-Vo)
cdz = u*/(-1ln(z/z0))
Norwegian Meteorological Institute met.no
Coupling time-scheme
T1
MI-IM MICOM or MIPOM
FT,FS,T(x),T(y) TO,SO,UO,VO,HS,Wfrz
FT,FS,T(x),T(y) TO,SO,UO,VO,HS,Wfrz
T1
T2 T2
Norwegian Meteorological Institute met.no
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 (2/f). • MIPOM can be unstable for very thin
surface sigma-layers. – Implicit calculation of ice-ocean stress
inside MIPOM is required
Norwegian Meteorological Institute met.no
1992 02
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1993 02
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1994 02
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1995 02
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1996 02
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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.
Norwegian Meteorological Institute met.no
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