OMIP contribution to CMIP6: experimental and diagnostic protocol for the physical component of the Ocean Model Intercomparison Project

Abstract

Abstract. The Ocean Model Intercomparison Project (OMIP) is an endorsed project in the Coupled Model Intercomparison Project Phase 6 (CMIP6). OMIP addresses CMIP6 science questions, investigating the origins and consequences of systematic model biases. It does so by providing a framework for evaluating (including assessment of systematic biases), understanding, and improving ocean, sea-ice, tracer, and biogeochemical components of climate and earth system models contributing to CMIP6. Among the WCRP Grand Challenges in climate science (GCs), OMIP primarily contributes to the regional sea level change and near-term (climate/decadal) prediction GCs.OMIP provides (a) an experimental protocol for global ocean/sea-ice models run with a prescribed atmospheric forcing; and (b) a protocol for ocean diagnostics to be saved as part of CMIP6. We focus here on the physical component of OMIP, with a companion paper (Orr et al., 2016) detailing methods for the inert chemistry and interactive biogeochemistry. The physical portion of the OMIP experimental protocol follows the interannual Coordinated Ocean-ice Reference Experiments (CORE-II). Since 2009, CORE-I (Normal Year Forcing) and CORE-II (Interannual Forcing) have become the standard methods to evaluate global ocean/sea-ice simulations and to examine mechanisms for forced ocean climate variability. The OMIP diagnostic protocol is relevant for any ocean model component of CMIP6, including the DECK (Diagnostic, Evaluation and Characterization of Klima experiments), historical simulations, FAFMIP (Flux Anomaly Forced MIP), C4MIP (Coupled Carbon Cycle Climate MIP), DAMIP (Detection and Attribution MIP), DCPP (Decadal Climate Prediction Project), ScenarioMIP, HighResMIP (High Resolution MIP), as well as the ocean/sea-ice OMIP simulations.

The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) contribution to CMIP6: investigation of sea-level and ocean climate change in response to CO<sub>2</sub> forcing

“…These standard diagnostics provide a large amount of information which will support many kinds of analysis that cannot be anticipated in detail. The standard ocean diagnostics are described in detail for the Ocean Model Intercomparison Project (OMIP) by Griffies et al (2016) in this issue, and in Table 3 we list a subset of particular importance to FAFMIP, for which they are priority 1 as monthly means. We refer to them here by their CMIP "short names".…”

“…These diagnostics are described in detail in Appendix L of Griffies et al (2016). Different models parametrise interior transports in many ways, so for the purpose of intercomparison it is necessary to aggregate them into broad classes.…”

“…Diagnostics of vertical and lateral tracer diffusivity detailed in Appendices M and N of Griffies et al (2016) are also requested at priority 1 as annual means. The tendency and diffusivity diagnostics should be included in the DECK 1pctCO2 and abrupt4xCO2 experiments, and in the piControl experiment, at least in the portion which is parallel to the FAFMIP experiments as well as in the FAFMIP experiments.…”

North Atlantic deep water formation and AMOC in CMIP5 models

“…A full assessment of the impact of resolution and model code changes is not possible with the limited data used here. In fact, this is the motivation for the CORE-II (Danabasoglu et al, 2014) and upcoming OMIP (Griffies et al, 2016) exercises. It is nonetheless interesting to note how differently models which share components behave.…”

Compiled records of carbon isotopes in atmospheric CO<sub>2</sub> for historical simulations in CMIP6

“…The specialized experiments focus on individual processes or time periods and they are referred to as CMIP6-endorsed MIPs, which are organized by separate committees. Ocean MIP (OMIP) focuses on historical ocean physics and biogeochemistry and provides a separate set of simulation protocols including climatic forcing provided by atmospheric reanalyses (Griffies et al, 2016;Orr et al, 2017). The Coupled Climate-Carbon Cycle MIP (C4MIP) encompasses historical, future, and idealized biogeochemical simulations in both the ocean and the terrestrial biosphere, using climatic forcing from coupled Earth system models (ESMs) as opposed to observations (Jones et al, 2016).…”