New Studies Conducted To Understand Modern Form Of Global Overturning Circulation (Goc).

Why in news

• GOC refers to equatorward transport of cold, deep waters and poleward transport of warm, near-surface waters.
  • It is responsible for transport of carbon and heat among ocean basins and between ocean and atmosphere.
• GOC is a system of two connected overturning cells:
  • Upper cell is linked to formation of North Atlantic Deep Water (NADW) and its shallower return flow to form Atlantic Meridional Overturning Circulation (AMOC).
  • Lower cell (referred as Southern Ocean Meridional Overturning Circulation) is associated with formation of Antarctic Bottom Water (AMM) and its return flow as Pacific Deep Water (PDW).
• Studies have indicated that tectonically driven changes in ocean gateways such as closure of Central American Seaway (CAS), since late Miocene period, had impacted GOC.
  • CAS is a body of water that once separated North America from South America.
• Now, National Centre for Polar and Ocean Research reconstructed Deep Water Circulation record of Indian Ocean and provided evidence in support of theory that closure of CAS led to evolution of modern form of GOC.
  • Indian Ocean does not have any major deep-water formations of its own. It acts only as a host for both GOC components.