Benshila, Rachid

Bourdallé-Badie, Romain

Colas, François

Coquart, Laure

Hourdin, Christophe

Madec, Gurvan

Maisonnave, Éric

Masson, Sébastien

Mazauric, Cyril

Meurdesoif, Yann

Samson, Guillaume

Valcke, Sophie

HAL-CEA

Tropical Channel NEMO-OASIS-WRF Coupled simulations at very high resolution Masson, S.*, C. Hourdin*, R. Benshila*, E. Maisonnave, Y. Meurdesoif★, C. Mazauric✪, G. Samson, F. Colas*, G. Madec*, R. Bourdalle-Badie, S. Valcke, L. Coquart * LOCEAN-IPSL,  CERFACS, ★LSCE-IPSL, ✪Bull S.A, Mercator-ocean started: 1 february 2012 	length: 39 months	equivalent of 6 persons full time	Our project ‣  identify, quantify upscalling processes	‣  propose an original solution...	SST	SST mean bias of IPCC models 	small scales ⇔ large scales Regional models	multi scales 	coupled models	•  Original methodology	•  Optimum use of resources	•  Prepare future climate models	Global models	Upscalling processes in coastal upwelling aeras 	1. Quantify the impact of small scale processes on global climate 	2. Reduce large scale and recurrent biases in climate simulations	Combine the advantages of regional and global models Our models •	Atmosphere : The Weather Research and Forecasting (WRF) 	•	Ocean: NEMO (Consortium of 6 European patterns)  is a state-of-the-art modeling framework for oceanographic research, operational oceanography seasonal forecast and climate studies.	•	Coupler: OASIS3-MCT software is allowing synchronized exchanges of coupling information between numerical codes representing different components of the climate system. Portability and flexibility are OASIS key design concepts and the reason of its success (Meteo France, IPSL, ECMWF, Met-Office, EC-Earth community, CMCC, MPI-Met…). 	Our methodology step 1: Tropical Channel (45°S - 45°N) 	27km resolution in ocean and atmosphere	Compare the climate mean sate, variability and biases in a set of coupled experiments with resolutions of 27km to 9km (in zooms or at global scale).  step 2: embedded zooms only in 1 component (ocean or atmosphere) of the coupled model	27km tropical channel + 9km zooms	step 3: embedded zooms on both components (ocean and atmosphere) of the coupled model.	27km tropical grid + 9km zooms	Step 4: Tropical Channel (45°S - 45°N) 	9km resolution in ocean and atmosphere	Where are we now? 9km tropical Channel (45°S-45°N) 	8204 WRF 6h elapsed /1 month.  1.1To/months  2 × 2 years 1024 NEMO 3 years of spin-up • WRF Single-Moment 6-Class Microphysics	• longwave Rapid Radiative Transfer Model 	• Dudhia shortwave radiation	• MM5  Monin-Obukhov scheme	• unified Noah land-surface model	• Yonsei University PBL	•       Kain-Fritsch (new Eta) scheme	•  or Betts-Miller-Janjic scheme 	8204 WRF 512 NEMO first tests: 1 month numerical performances WRF WRF+NEMO = +5% 6h outputs 5s 10s elapsed time model time-step SST from coupled expériment	OLR results... 10m wind speed OLR 

Tropical Channel NEMO-OASIS-WRF Coupled Simulations at Very High Resolution

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