A suite of standard ocean hydrographic and circulation metrics are applied to the equilibrium physical solutions from thirteen global carbon models participating in phase 2 of the Ocean Carbon-cycle Model Intercomparison Project (OCMIP-2). Model-data comparisons are presented for sea surface temperature and salinity, seasonal mixed layer depth, meridional heat and freshwater transport, 3-D hydrographic fields, and meridional overturning. Considerable variation exists among the OCMIP-2 simulations, with some of the solutions falling noticeably outside available observational constraints. For some cases, model-model and model-data differences can be related to variations in surface forcing, sub-grid scale parameterizations, and model architecture. These errors in the physical metrics point to significant problems in the underlying model representations of ocean transport and dynamics, problems that directly propagate into the OCMIP predicted ocean tracer and carbon cycle variables (e.g., air-sea CO2 flux; chlorofluorocarbon and anthropogenic CO2 uptake; export production). The substantial model-model ranges in OCMIP-2 biogeochemical fields (±25-40%), therefore, likely overestimate the uncertainties in ocean carbon cycle dynamics due to large-scale physical circulation.
EPIC Alfred Wegener Institut