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www.mercator-ocean.fr MERCATOR OCEAN MODELISATION 1/12° configurations 1. North Atlantic Ocean 2. Global
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MERCATOR OCEAN MODELISATION
1/12° configurations
1. North Atlantic Ocean
2. Global
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North Atlantic configurations.
Ocean code: NEMOGrid: ORCABathymetry: ETOPO + BetMAP + GebcoInitialisation:
LevitusParameterizations: • Filtered free surface • Partial steps• LIM ice model • Isopycnal laplacian diffusion for the tracers• Biharmonic diffusion on the dynamic • Energy and enstrophy conservating scheme• Monthly climatology for the runoff file (Dai & Trenberth)• CLIO Bulk formula•Atmospheric forcing available: Daily mean ECMWF operational analyses (period: 1998-2006) Daily mean ERA40 (1992-2001)
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ATL12-T03 simulation
• ATL12-T03 configuration: Domain : 1608 x 1551 x 46 Vertical grid refined at the surface : 46 z-levels (1 to 450m) (DRAKKAR : 46 z-levels (6 to 250 m))
• Atmospheric forcing : ECMWF operational analyses 2000-2006 :
“Spin up” : twice the year 2000 CLIO bulk formula Daily mean forcing flux No sss relaxation
• Outputs : Fields : 3 days mean. monthly restart files.
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General circulation : 2003 Sea Surface Height
SSH 2003ATL12-T03
MSSH 93-99(M.H. Rio )
-1m 0.86m
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EKE 2004ATL12-T03EKE 2004
Topex/Poseidon EKE 2004
0 1000
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19.124.4
25.7
32
30.4
3.6 2.60.8
5.6
0.63
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Comparison Gulf stream :ATL12-T03 / Altimetry (aviso)
37N
Good location of the Gulf Stream front Cold cells southern of the GS(Same size but more frequent and colder)
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Mediterranean EKE in 2003
Courtesy of PHD I.Pujol 2006
• Good variability of the Algerian current and Alboran gyre • Strong coastal current in Levantine basin compare to altimetry.
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Conclusions
Well reproduced general circulation : GS separation, NAC, North Brazil current,…
Variability comparable to the altimetry data
Problems :
Boundaries limits different from NATL4
Large scale factors between 50-500m induce instabilities :
No realisticoscillations
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ATL12-T09 : Domain
ATL12-T09
NATL4
ATL12-T03
North and south boundaries are now similar to the NATL4 configuration
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ATL12-T09 : Bathymetry
First and last indices of ATL12-T09 domain are issued from the 1/4° bathymetry to prepare OBC with ORCA025 fields.
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Decrease ITCZ intensity (tests performed with NATL4)
Simulation performed with precipitation not corrected
Simulation performed with the threshold function over the precipitation field at the
equator.
Threshold function applied to the
precipitation field between 10°N and
10°S
Difference of the SSS : Levitus annual - NATL4 annual (year 3)Réductions en %
mm/jours
Improvment of the SSS in the tropics.No degradation in the north Atlantic basin.Impact of the correction limited to upper layers (<50m>)
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ATL12-T09 : computing
• ATL12-T09 configuration: Domain : 1615 x 1585 x 50 Vertical grid refined at the surface : 50 z-levels Initial conditions from Levitus climatology
• Atmospheric forcing : ECMWF operational analyses 1998-2006 :
CLIO bulk formula Daily mean forcing flux SSS relaxation
• Outputs : Fields : 3.3Go/date
3 days mean. 1 year : 60h elapsed on 224proc (with SMT, 112 “real”)
Total of outputs for the simulation : 2 To
Jpni, jpnj: 24, 13Jpnij : 224 (-88proc)
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New vertical grid (50 levels)
Different vertical grids
Scales factors
50 Levels
Temperature (high) and zonal velocity (bottom) at the equator. (date : y2004m07d22)
46 Levels
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ATL12-T09 : Results
y2001 y2002 y2003
Max=15.5 Max=17.4 Max=18.8
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ORCA12 : computing
• ORCA12 configuration: Domain : 4322 x 3059 x 50 Vertical grid refined at the surface : 50 z-levels Memory needed: 510 Go
• Atmospheric forcing : ECMWF operational analyses 1998-2006 :
CLIO bulk formula Daily mean forcing flux SSS relaxation ?
• Outputs : Fields : 18Go/date (4.5Go in 4bytes)
3 days mean.
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Prospects
Studies :• Diurnal cycle (3H) NATL4• Tidal mixing parameterization.• Wave mixing• Test OBC European regional models• lntercomparaison OPA-Symphonie (biscay bay) and extension to OPA-Symphonie-Mars-Hycom
Simulations : • Simulation Bulk MEMO_UNITFP with ORCA025_LIM (1998-
2006)• First ORCA12 simulation.• Development configuration of the European coast (1/36°)
