OCMIP Background

Three-dimensional ocean models were first employed to study the ocean's carbon cycle about 20 years ago. Computer technology has since advanced rapdily, and now many scientists use 3-D models to study ocean circulation. Others have built on these developments to study ocean biogeochemistry, for which ocean circulation is a primary control.  These models provide test beds for hypotheses of how the ocean's carbon cycle operates.  They also provide tools for spatiotemporal interpolation and prediction.  Yet as is the case for the man with two watches, different models produce different results.  Advances in ocean carbon-cycle modeling have been impeded by the inability to compare inconsistent simulations and even inconsistent practices of model-data comparison. 

Recognizing that these hindrances slow the development of ocean carbon-cycle models, the IGBP initiated the Ocean Carbon-Cycle Model Intercomparison Project (OCMIP) in 1995 through the Global, Analysis, Interpretation, and Modeling (GAIM) Task Force.  OCMIP's goal has been to identify and understand differences between existing 3-D global ocean carbon-cycle models and thus accelerate their development.  In 1995, four models began to make simulations for natural and anthropogenic CO2 and C-14, following standard protocols agreed upon by participants.  Resulting output was analyzed in consistent manner at a central location.  This was the first phase of this project, now known as OCMIP-1.

During the second phase OCMIP-2 (1998-2002), thirteen model groups made new simulations of CO2 ad C-14, they implemented a common biological model, which included O2 as a tracer, and they made separate simulations for CFC-11, CFC-12, and He-3 to evaluate ocean circulation. Work continues to exploit the model output archive generqted by OCMIP-2. Ongoing work also includes three newly funded activities (modeling interannual variability, ocean inverse-basis modeling, and automating model-data comparison) that together form OCMIP-3.