Scott C. Doney, Department of Marine Chemistry and Geochemistry, Woods
Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
Keith Lindsay, Climate and Global Dynamics Division, National Center
for Atmospheric Research, Boulder, Colorado, USA
Ken Caldeira, Climate System Modeling Group, Lawrence Livermore
National Laboratory, Livermore, California, USA
Jean-Michel Campin1 and Anne Mouchet,
University of Liege, Liege, Belgium
Helge Drange and Yongqi Gao, Nansen Environmental and Remote Sensing
Center, Bergen, Norway
Jean-Claude Dutay and James C. Orr, Laboratoire des Sciences du Climat
et de l'Environnement, Gif-sur-Yvette, France
Mick Follows and John C. Marshall, Earth Atmospheric and Planetary
Sciences Department, Massachusetts Institute of Technology, Cambridge,
Massachusetts, USA
Anand Gnanadesikan, Jorge Sarmiento, and Rick Slater, Atmospheric
and Oceanic Sciences Program, Princeton University, Princeton, New
Jersey, USA
Nicolas Gruber, University of California, Los Angeles, California, USA
Akio Ishida and Yasuhiro Yamanaka, Institute for Gobal Change
Research, Yokohama, Japan
Fortunat Joos and Gian-Kasper Plattner2, Climate and Environmental Physics,
Physics Institute, University of Bern, Bern, Switzerland
Gilles Madec, Laboratoire d' Oceanographie Dynamique et de
Climatologie Paris, Paris, France
Ernst Maier-Reimer, Max Planck Institut für Meteorologie, Hamburg,
Germany
Richard J. Matear, Commonwealth Science and Industrial Research
Organization, Hobart, Australia
Patrick Monfray, Laboratoire d' Etudes en Geophysique et Oceanographie
Spatiales, Toulouse, France
Ray Najjar, Pennsylvania State University, State College,
Pennsylvania, USA
Reiner Schlitzer and Marie-France Weirig, Alfred Wegener Institute for
Polar and Marine Research, Bremerhaven, Germany
Ian J. Totterdell and Andrea Yool, George Deacon Division and
Department of Oceanography, Southampton Oceanography Centre,
University of Southampton, Southampton, England
1Now at Earth Atmospheric and
Planetary Sciences Department, Massachusetts Institute of Technology,
Cambridge, Massachusetts, USA
2Now at Institute of Geophysics and
Planetary Physics, University of California, Los Angeles, Los Angeles,
California, USA
A suite of standard ocean hydrographic and circulation metrics are applied to the equilibrium physical solutions from 13 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, subgrid-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 affect the OCMIP predicted ocean tracer and carbon cycle variables (e.g., air-sea CO2 flux, chlorofluorocarbon and anthropogenic CO2 uptake, and export production). A substantial fraction of the large model-model ranges in OCMIP-2 biogeochemical fields (±25-40%) represents the propagation of known errors in model physics. Therefore the model-model spread likely overstates the uncertainty in our current understanding of the ocean carbon system, particularly for transport-dominated fields such as the historical uptake of anthropogenic CO2. A full error assessment, however, would need to account for additional sources of uncertainty such as more complex biological-chemical-physical interactions, biases arising from poorly resolved or neglected physical processes, and climate change.