Meridional overturning circulation and heat transport observations in the Atlantic Ocean [in 'state of the Climate in 2012']

The meridional overturning circulation (MOC) is typically defined as the maximum of the zonallyintegrated mass transport stream function. In the Atlantic Ocean the MOC is the large-scale circulation that transports warm near-surface water northward, thereby transferring heat to the atmosphere and returning southward as colder, denser, deeper water. The actual flows are more complicated than this simple description and for further details the reader should see previous State of the Climate reports (e.g., Baringer et al. 2011, 2012) or the recent reviews of Srokosz et al. (2012) or Lozier (2012).