Global Overturning Circulation (GOC)

Global overturning circulation is responsible for the transport of carbon and heat among the ocean basins and between the ocean and the atmosphere. The GOC can be conceptualized primarily into two connected overturning as follows –

• The upper cell is linked to the formation of North Atlantic Deep Water (NADW) and it’s shallower return flow to form the Atlantic meridional overturning circulation (AMOC), roughly in the depth range of 1500-3500m.
• The lower cell is associated with the production of Antarctic Bottom Water (AABW) which occupies the deeper parts of the abyssal ocean, and it’s return flow mostly as pacific deep water (PDW) and is referred to as the southern ocean meridional overturning circulation (SOMOC)

These two circulation cells are interconnected via upwelling in the southern ocean where deep water are mixed in the circumpolar circulation. Part of resultant mixture contributes to AABW formation locally, and rest converts to less dense water-mass transported northward at intermediate and shallower depths such as Antarctic Intermediate water.