Nereus Project, réunion Océano, Toulouse, 30/09/2008 Journée de rencontre Météo France/Mecator/Océan 14 Juin 2010 1 Activités de la modélisation de la

Journée de rencontre Météo France/Mecator/Océan 14 Juin 2010

1

Activités de la modélisation de la banquise à Mercator

G. Garric (Mercator Océan) et R. Bourdallé-Badie (CERFACS)

The Model LIM2 in the Mercator systems. Current status of sea ice in the global ¼°operational system Recent advances

The update LIM2_EVPDiurnal cycle (and ERAinterim)

Tests of LIM2_EVP in the global eddy-resolving model (1/12°) Conclusions and Plans


Global systems 2° Low resolution (PSY2G2). Last release in June 2008 (ON since September 2003)

(target : IC for seasonal prediction, reanalysis). ¼° Eddy permitting (PSY3V2). Last release in February 2008 (ON since October 2005)

(target MYOcean, reanalysis, climate monitoring, sea ice, biogeochemistry…) Sea ice forecasts.

1/12° Eddy resolving (PSY4). Demonstration phase in April 2008 for MERSEA. (target : MYOcean, biogeochemistry) Sea ice forecasts.

North Atlantic and Mediterranean Sea systems 1/12° Eddy resolving (PSY2V3) Last release in July 2008 (ON since September 2003)

(target: mesoscale upper ocean, downscaling to regional and coastal systems) Sea ice forecasts.

1/12° Eddy resolving (PSY2Q1). Operated daily. ON since June 2008 (target : navy) Sea ice forecasts.

IBI (Iberian, Biscayan and Irish) system 1/36° Eddy resolving + tides (PSY ??) Still in development R&D part. (target: backup

MYOcean, tides)

Current status of Mercator systems

Several model configurations operated for several uses


The Thermodynamic-Dynamic model LIM2Collaboration with UCL, Louvain-la-Neuve, Belgium

3-layers model (Semtner, 1976)- 1D vertical diffusion of heat

- Surface temperature, brine pockets,

snow/iceformation …

- Leads parameterisation

Transport : Advective scheme from Prather (1986)

- Viscous-Plastic rheology from Hibler (1979)

- Ice/ocean drag damping necessary (1/4° and 1/12°)

THERMODYNAMICSDYNAMICS

Fichefet and Maqueda,Sensitivity of a global sea ice model to the treatment of ice thermodynamics and dynamics, JGR (1997).

Fichefet and Maqueda, Modelling the influence of snow accumulation and snow-ice formation on the seasonal cycle of the Antarctic sea ice cover, Clim. Dyn. (1999).

Goosse and Fichefet, Importance of ice-ocean interactions for the global ocean circulation: a model study, JGR (1999).

Timmermann et al., On the representation of high latitude processes in the ORCA-LIM global coupled sea ice-ocean model, Ocean Modelling, (2005).


Current status of sea ice in operationnal systems Global ¼° configuration (no assimilation of sea ice)

AGU fall meeting 2008

Global ¼° configuration Operationnal system

IFREMER/CERSATSatellite data

Slight overestimationin winters

September 2008

March 2007

March 2007

September 2008


AGU fall meeting 2008

September 2008 March 2007

Overestimationin summers

Current status of sea ice in operationnal systems Global ¼° configuration (no assimilation of sea ice)

Global ¼° configurationOperationnal system

IFREMER/CERSATSatellite data

September 2008 March 2007


Current status of sea ice in operational systems Global ¼° configuration (no assimilation of sea ice)Ice Speed

IFREMER/CERSATGlobal ¼° operational system


Recent advances - The update LIM2_EVP

- Newly sea ice formed in leads set to 0.6m in NH and 0.5m in SH

- Less snowfalls during NH summertime.

- EVP (Hunke and Dukowicz,1997) (time scale for elastic waves : 3600s and 360 nbr of iterations for subcycling.

- Refreshed ice/ocean drag at each oceanic time step

THERMODYNAMICS DYNAMICS

Bouillon et al., An elastic-viscous-plastic sea ice model formulated on Arakawa B and C grids, Ocean Model., (2009).


Sea ice thickness(March 2007)

Closer agreement in summer Expected thickness distribution

Sep

t 20

07

IFREMER/CERSAT Satellite Data


Global ¼° configurationLIM2_EVP



Arctic ice coverage anomaly wrt mean seasonal cycle 2001-2007

2001 2008 2001 2008 2001 2008

-175 800 km2/yr-159 400 km2/yr -173 900 km2/yr

Better capture of the recent trend

IFREMER/CERSATSatellite Data

Global ¼° configuraitionLIM2_EVP




Recent advances - The update LIM2_EVPIce Speed

Slight increase of Ice speed with LIM2_EVP.IFREMER/CERSAT LIM2

LIM2_EVP

February 2002

LIM2_EVP

IFREMER/CERSAT LIM2

November 2002


- Correlation of 0.66- CERSAT (2002-2008): +2.7.10-2 km/day/year - LIM2_EVP (2002-2008): +1.5 .10-2 km/day/year - IABP (1979-2007): +5.6 .10-2 km/day/year (Rampal et al., 2009)

Recent advances - The update LIM2_EVPIce Speed.

Monthly mean ice speed (CERSAT region) (km/day)

CERSAT

LIM2_EVP


AntarcticArctic

Sea ice extent monthly anomalies

Pb with Initial Conditions

Pb with the seasonal cycle:too much sea ice in summer

Correlation: 0.8

GLORYS with LIM2_EVP

IFREMER/CERSAT


Mercator reanalysis GLORYS1V1 (no sea ice assimilation)Interannual variability 2002-2007


3h forcing (ECMWF)

Recent advances - Impact of diurnal cycle (3H)

RMS of the wind zonal stress over y2003

Daily forcing (ECMWF)Daily3h

20/09/2003 25/10/2003


CERSAT Data Daily Forcing

Sea Ice FractionMarch 2003

3H Forcing

Ice Thickness

Ice FractionIce Fraction

Ice Thickness

Recent advances - Impact of diurnal cycle (3H)


IFREMER/CERSAT LIM2

LIM2_EVP

February 2002

LIM2_EVP 3H Forcing

Recent advances – Impact of diurnal cycle (3H) Tests with ECMWF ERAinterim

Large increase of ice speed.

LIM2_EVP

IFREMER/CERSAT LIM2

November 2002

LIM2_EVP 3H Forcing


Monthly mean ice speed (CERSAT region) (km/day)

Recent advances – Impact of diurnal cycle (3H) Tests with ECMWF ERAinterim


Tests with the global eddy-resolving model (1/12°). LIM2_EVP/3H Forcing

IFREMER/CERSAT Old ORCA12 New ORCA12

16th March 2002

Insufficient sea ice during summer


Tests with the global eddy-resolving model (1/12°).LIM2_EVP/3H Forcing

IFREMER/CERSAT Old ORCA12 New ORCA12

11th September 2002

Insufficient sea ice during summer


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Plans

Implementation of LIM2_EVP in the real time operational systems. Work on the impact of the Diurnal Cycle (3H) in ¼° and 1/12° to be

continued. Correction of summer bias : use of ERAinterim reanalysis for reanalysis

purposes. Use of Thermodynamics of LIM3 in 2011? with melting ponds? Dynamics (rheology + sea ice drag) in ¼ and 1/12°: rheology EVP at 1/12°

? Use of sea ice data delivered by MyOcean for validation.

2012 (target V2 MyOcean): Global 1/12° with LIM2_EVP or LIM3

Seasonal forecasts with atmospheric forcing from Meteo France? Sea ice reanalysis as a reference for recent years?

Thank you!!



AntarcticArctic

Sea ice extent monthly anomalies

Pb with Initial ConditionsCorrelation: 0.8

GLORYS with LIM2_EVP

IFREMER/CERSAT

Recent advances – Initial conditions (for sea ice mass)

Mercator reanalysis GLORYS1V1 (no sea ice assimilation)Interannual variability 2002-2007

Pb with the seasonal cycle:too much sea ice in summer


Control (model)Reconstructionfrom concentration

Example : Thickness=f(Ice Surf. Temperature)

Th

ick

nes

s

Reconstructionfrom temperature

Application to observation of temperature and concentration

Recent advances - Initial conditions (for sea ice mass) Get an initial sea ice mass already in equilibrium with the model.


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Arctic AntarcticSea ice extent monthly anomalies

No noticeable spin up

IFREMER/CERSAT

Global ¼° experiment

Recent advances - Initial conditions (for sea ice mass) Get an initial sea ice mass already in equilibrium with the model.


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Needs of accurate high resolution of sea ice data…

Tests with the global eddy-resolving model (1/12°).

1/12° resolution in Antarctica


The model configurations

► 1 code : NEMO (LIM)

► 1 grid : all the configurations are on the same ORCA (tripolar) grid

► One single input dataset : initialization and forcing (ECMWF analysis and forecasts)

► Some of these configurations are shared with the scientific and operational community ORCA025: Drakkar and

Glorys Project, Barnier et al. UKMO, CMCC, EC, DFO, …

ORCA025 ¼°

1 point sur 12

ORCA12 1/12°ATL12 1/12°NEATL36 1/36°

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Nereus Project, réunion Océano, Toulouse, 30/09/2008 Journée de rencontre Météo France/Mecator/Océan 14 Juin 2010 1 Activités de la modélisation de la