The Ocean Carbon-Cycle Model Intercomparison Project (OCMIP) was initiated by IGBP/GAIM in 1995 as a means to develop international collaboration to jointly improve the predictive capacity and accelerate development of global-scale, three-dimensional, ocean carbon-cycle models through standardized model evaluation and model intercomparison. Ocean carbon-cycle models are used to simulate ocean uptake and loss of carbon and to constrain the ocean's role in the global carbon cycle. After a 3-year pilot study with 4 models (OCMIP-1), a second phase with 13 modeling groups and 2 data specialist groups took on a more detailed comparison during 1998-2001. OCMIP-2 addressed the preindustrial state of the ocean as well as its present and future perturbations. Modeling groups made common simulations for carbon, related biogeochemical tracers, and circulation tracers. Many groups also made simulations to evaluate the efficiency of purposefully injecting CO2 into the deep ocean and to evaluate the potential of mantle He-3 and He-4 to be used as tracers of deep-ocean circulation. OCMIP is now in its third phase, since 2002. Three separately funded OCMIP-3 projects focus on simulating interannual to decadal variability, inferring air-sea CO2 fluxes from related measurements in the interior ocean, and on automating standard analysis of model output.


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