Members G. Danabasoglu (co-chair) National Center for Atmospheric Research, USA

1. CLIVAR Imperative IV: Improved atmosphere and ocean component models of Earth System Models Members G. Danabasoglu (co-chair) National Center for Atmospheric Research, USA H. Drange (co-chair) University of Bergen, Norway M. Marsland CSIRO, Australia S. Griffies Geophysical Fluid Dynamics Lab., NOAA, USA G. Madec LODYC, Institute Pierre Simon Laplace, France R. Greatbatch Institut für Meereskunde, Kiel, Germany H. Tsujino Met. Res. Inst., Japan Meteorological Agency, Japan E. Curchitser Rutgers University, USA Emeritus C. Böning Institut für Meereskunde, Kiel, Germany A. M. Treguier Laboratoire de Physique de Océans, IFREMER, France R. Gerdes Alfred Wegener Inst., Germany E. Chassignet Florida State University, USA Organizer A. Pirani ICPO Boulder, 23-26 Sep 2010

2. Two parallel approaches Model simulations and analysis Model development Level, layer and hybrid models Resolution & parameterizations Numerics (accuracy, efficiency, consistency, etc.) Test-bed for development of the ocean component in ESMs Biogeochemistry (particularly CO2 and ocean acidificaiton) and tracers Ice shelves (coming) Downscaling/shelf modelling

3. Curchitser et. al.

4. Two parallel approaches Model simulations and analysis Model development Level, layer and hybrid models Resolution & parameterizations Numerics (accuracy, efficiency, consistency, etc.) Test-bed for development of the ocean component in ESMs Biogeochemistry (particularly CO2 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

5. Main WGOMD activities (i) Workshops facilitating collaboration, communication, education - 2004 Princeton State of the Art in Ocean Climate Modelling - 2005 Hobart State of the art in Southern Ocean Modelling - 2007 Bergen Numerical Methods for Ocean Models - 2009 Exeter Ocean Mesoscale Eddies: Repr, Parameterizations, Obs - 2010 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

6. 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-I Multi-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-III Fresh water melt perturbation idealizing the melt of water around Greenland (Gerdes et al., 2006, Ocean Modelling) • CORE IV Heat perturbation / partial coupling (being discussed)

7. Ongoing WGOMD synthesis work • Spin-upbehaviourof CORE-IAF simulations(typically 4 cycles or more) • global, and basinscale • Hovmollerof heat transports • time series for global mean heat and fresh water enteringtheoceansurface • time series of AMOC, PDO, subpolargyreindex, … throughflows, overflows,… • seaice area, extent, thickness • global and basin SSH time series • water masstransformation • … Generate an archive of model output Analysis of multi-model results Working group+ meeting, Jan 2012 in Venice

8. Example of spin-up of OGCMs Max overturning (Sv)

9. Example of spin-up of OGCMs Strong SSS relaxation Weak SSS relaxation + restoring Max overturning (Sv)

10. Ongoing WGOMD synthesis work • 1988-2007 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

11. Ongoing WGOMD synthesis work • Variability defined with respect to 1988-2007 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

12. 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

13. 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 Intention to duplicate part of the analysis to the CMIP5 ensemble

14. Sensitivity experiments

15. Post 1995 forcing Control integration (1995; “real model world”) Lohmann et al.

17. 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) * http://www.clisap.de/Easy-INIT.easyinit.0.html * presently 8 (?) reanalyses are (more or less) available for comparison and analysis