Global meridional overturning circulation revisited

What is it about?

In order to better understand the global meridional overturning circulation (GMOC), here we carry out a global ocean model simulation with its temperature and salinity corrected toward observations. The derived GMOC is presented, validated against observations and summarized in a schematic, which highlights several important but relatively underexplored aspects of the GMOC, including the pathway through which the heaviest water mass formed around the Antarctica is brought to the surface. This and other key aspects of the GMOC are poorly captured in a model run without the temperature and salinity corrections, suggesting that current climate models do not reproduce realistic paths of the GMOC and the associated global heat, salt and carbon balances.

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Why is it important?

Ocean tracers such as heat, salt and carbon are perpetually carried by the global meridional overturning circulation (GMOC) and redistributed between hemispheres and across ocean basins from their source regions. The GMOC is therefore a crucial component of the global heat, salt and carbon balances.