A description of Model Intercomparison Processes and Techniques for Ocean Forecasting

Abstract. The availability of numerical simulations for ocean past estimates or future forecast worldwide at multiple scales is opening new challenges in assessing their realism and predictive capacity through an intercomparison exercise. This requires a huge effort in designing and implementing a proper assessment of models’ performances, as already demonstrated by the atmospheric community that was pioneering in that sense. Historically, the ocean community launched only in the recent period dedicated actions aimed at identifying robust patterns in eddy-permitting simulations: it required definition of modelling configurations, execution of dedicated experiments that deal also with the storing of the outputs and the implementation of evaluation frameworks. Starting from this baseline, numerous initiatives like CLIVAR for climate research and GODAE for operational systems have raised and are actively promoting best practices through specific intercomparison tasks, aimed at demonstrating the efficient use of the Global Ocean Observing System and the operational capabilities, sharing expertise and increase the scientific quality of the numerical systems. Examples, like the ORA-IP, or the Class 4 near real time GODAE intercomparison are introduced and commented, discussing also on the ways forward on making this kind of analysis more systematic for addressing monitoring of ocean state in operations.