Contact:  Gokhan Danabasoglu

The CORE framework defines protocols for performing global ocean – sea-ice coupled simulations forced with common atmospheric data sets, using the same bulk formulas. The first phase of this project, namely CORE-I, involved using an idealized, i.e., synthetically constructed, one-year repeating cycle of forcing, referred to as normal year forcing. The primary goal was to investigate and document the climatological mean ocean and sea-ice states obtained after long (at least 500 years) integrations.

The second phase of COREs, CORE-II, uses inter-annually varying atmospheric forcing over the 60-year period from 1948 to 2007. In the oceanographic community, the CORE-II simulations are usually referred to as hindcast experiments. These hindcasts provide a framework to evaluate ocean and sea-ice model performance and study mechanisms of time-dependent ocean phenomena and their variability from seasonal to decadal time scales for the recent past. Specifically, the CORE-II hindcast experiments directly contribute to: i) evaluation, understanding, and improvement of the ocean components of earth system models; ii) investigation of mechanisms for seasonal, inter-annual, and decadal variability; iii) attribution of ocean-climate events to forced and natural variability; iv) evaluation of robustness of mechanisms across models; and v) bridging observations and modeling, by complementing ocean reanalysis from data assimilation approaches. They also provide consistent ocean and sea-ice states that can be used for initialization of climate (e.g., decadal) prediction experiments. The CORE-II simulations from about twenty participating groups are being analyzed in several studies.

The CORE data sets are collaboratively supported by the National Center for Atmospheric Research (NCAR) and the Geophysical Fluid Dynamics Laboratory (GFDL) under the umbrella of the Climate Variability and Predictability (CLIVAR) Working Group on Ocean Model Development (WGOMD). All data sets, codes for the bulk formulas, technical report, and other support codes along with the release notes are freely available at Future releases of these data can be expected as improvements are made to the data products and to our understanding of their biases and as data become available for recent years (now available through 2009). The WGOMD is currently considering inclusion of COREs in the CMIP framework.


  • Danabasoglu, G., and Co-authors, 2013: North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Part I: Mean States. Ocean Modelling, doi: 10.1016/j.ocemod.2013.10.005.
  • Griffies, S. M., and Co-authors, 2009: Coordinated Ocean-ice Reference Experiments (COREs). Ocean Modelling, 26, 1–46.
  • Griffies, S. M., and Co-authors, 2012: Datasets and protocol for the CLIVAR WGOMD Coordinated Ocean sea-ice Reference Experiments (COREs). WCRP Report No. 21/2012.
  • Large, W. G., and S. Yeager, 2004: Diurnal to decadal global forcing for ocean and sea-ice models: The data sets and flux climatologies. NCAR Tech. Note NCAR/TN 460+STR.
  • Large, W. G., and S. G. Yeager, 2009: The global climatology of an interannually varying air-sea flux data set. Clim. Dyn., 33, 341–364