Members G. Danabasoglu(co-chair) National Center for Atmospheric Research, USA H. Drange (co-chair) University of Bergen, Norway M. MarslandCSIRO, Australia S. GriffiesGeophysical Fluid Dynamics Lab., NOAA, USA G. MadecLODYC, Institute Pierre Simon Laplace, France R. GreatbatchInstitut für Meereskunde, Kiel, Germany H. TsujinoMet. Res. Inst., Japan Meteorological Agency, Japan E. CurchitserRutgers University, USA Emeritus C. BöningInstitut für Meereskunde, Kiel, Germany A. M. TreguierLaboratoire de Physique de Océans, IFREMER, France R. GerdesAlfred Wegener Inst., Germany E. ChassignetFlorida State University, USA Organizer A. PiraniICPO Boulder, Sep 2010 Sea ice/ice shelvesOcean biogeochemOcean numerics D. Holland (USA)K. Fennell (Canada)G. Nurser (UK) CLIVAR Imperative IV: Improved atmosphere and ocean component models of Earth System Models

Two parallel approaches Model development Model simulations and analysis Level, layer and hybrid models Resolution & parameterizations Numerics (accuracy, efficiency, consistency, etc.) Test-bed for development of the ocean component in ESMs Biogeochemistry (particularly CO 2 and ocean acidificaiton) and tracers Ice shelves (coming) Downscaling/shelf modelling

Curchitser et. al.

Two parallel approaches Model development Model simulations and analysis Level, layer and hybrid models Resolution & parameterizations Numerics (accuracy, efficiency, consistency, etc.) Test-bed for development of the ocean component in ESMs Biogeochemistry (particularly CO 2 and ocean acidificaiton) and tracers Ice shelves (coming) Downscaling/shelf modelling Atmospheric forcing Spin-up procedure Model evaluation against observations Model comparison (but no MIP) Analysis of interannual to decadal variability Analysis of mechanisms Sensitivity experiments

Main WGOMD activities (i) Workshops facilitating collaboration, communication, education Princeton State of the Art in Ocean Climate Modelling Hobart State of the art in Southern Ocean Modelling Bergen Numerical Methods for Ocean Models Exeter Ocean Mesoscale Eddies: Repr, Parameterizations, Obs Boulder Decadal Variability, Predict, and Prediction: Role of the Ocean (ii) Coordinated Ocean-Ice Reference Experiments (CORE I-III) - Benchmark simulations, with detailed protocols, for global ocean-ice models (iii) Repository for Evaluating Ocean Simulations (WGOMD REOS) - Web-based tool for evaluating ocean simulations (iv) White papers - Hurrell et al. (2009), Decadal Climate Prediction: Opportunities and Challenges, OceanObs´09 - Griffies et al. (2009), Problems and Prospects in Large-Scale Ocean Circulation Models, OceanObs´09 - Griffies et al. (2008), Sampling Physical Ocean Fields in WCRP CMIP5 Simulations (v) Review and more specific peer-reviewed OGCM articles

CORE (Co-ordinated Ocean-Ice Reference Experiments) Provide a workable and agreeable experimental design for global ocean-ice models to be run for long-term climate studies; should be useful for experts and newcomers Establish a framework where the experimental design is flexible and subject to refinement as the community gains experience and provides feedback CORE-IMulti-century spin-up with repeating “Normal Year Forcing” (Large and Yeager, 2004; Griffies et al., 2009, Ocean Modelling) CORE-II: 1948-present; interannually varying forcing (Large and Yeager, 2004 & 2009) CORE-IIIFresh water melt perturbation idealizing the melt of water around Greenland (Gerdes et al., 2006, Ocean Modelling) CORE IV Heat perturbation / partial coupling (being discussed)

Spin-up behaviour of CORE-IAF simulations (typically 4 cycles or more) global, and basin scale Hovmoller of heat transports time series for global mean heat and fresh water entering the ocean surface time series of AMOC, PDO, subpolar gyre index, … throughflows, overflows,… sea ice area, extent, thickness global and basin SSH time series water mass transformation … Ongoing WGOMD synthesis work Generate an archive of model output Analysis of multi-model results Working group+ meeting, Jan 2012 in Venice

Helge Drange Geophysical Institute University of Bergen Max overturning (Sv) Example of spin-up of OGCMs

Helge Drange Geophysical Institute University of Bergen Strong SSS relaxation Weak SSS relaxation + restoring Max overturning (Sv) Example of spin-up of OGCMs

time mean diagnostics (best forcing, ok observational support) Poleward heat transport: global, Atlantic, Indo-Pacific Poleward fresh water transport: global, Atlantic, Indo-Pacific SST, SSS, SSH, MLD (wintertime and summertime mean) Overturning (global, Atlantic-Arctic, Indo-Pac) depth and sigma-2 space Zonal mean temp and salinity relative to observations Total heat flux, P-E+R entering ocean Map of restoring/correction salt flux converted to an implied water flux Hemispheric average annual cycle of sea ice Ongoing WGOMD synthesis work

Variability defined with respect to mean Standard deviations of annual mean SST, SSS, SSH, overturning streamfunction (depth and density by basin) MLD, summer, winter, mean, std Tropical thermocline std (across all basins) Tropical cells T14C depth standard deviation Outcropping, mean position, std Formation, propagation, decay of T/S-anomalies Upper ocean heat content anomaly Thermosteric and halosteric sea level Ongoing WGOMD synthesis work

Trends and changes Comparison with observed trends Look for shifts in Atlantic and Pacific to define The time mean minus the time mean SST, SSS, SSH Zonal mean temp and salinity Case studies for North Atlantic Indian Ocean Pacific Ocean Southern ocean Arctic Ocean Ongoing WGOMD synthesis work

Illustration of sensitivities Changes to precip at high latitudes Changes in zonal wind trend in Southern Ocean Role of buoyancy and mechanical forcing for abrupt shifts More general discussion of the role that CORE-II plays in helping feedback on the development of atmospheric states to force the ocean-ice models Ongoing WGOMD synthesis work Intention to duplicate part of the analysis to the CMIP5 ensemble

Helge Drange Geophysical Institute University of Bergen Sensitivity experiments

Helge Drange Geophysical Institute University of Bergen Post 1995 forcing Control integration (1995; “real model world”) Lohmann et al.

EasyInit project CLIVAR meeting on decadal predictions, at KNMI, November 2009: modeling community had suggested and requested that ocean reanalysis are being provided in an “EasyInit” project that can support the coupled modeling community to ease the initialization of decadal prediction runs using ocean reanalyses Aim: The modeling community can get all reanalysis in a “one-stop” fashion and with a uniform format Host: The KlimaCampus of the University of Hamburg (D. Stammer) * * presently 8 (?) reanalyses are (more or less) available for comparison and analysis