Is the NADW well oxygenated?
These well-oxygenated bottom waters originate from down-welling/thermohaline circulation in polar regions. Here North Atlantic Deep Water (NADW) is formed which feeds the upwelling in many other regions of the world ocean.
What is NADW and Aabw?
North Atlantic Deep water (NADW) is a water mass that is derived from the warm salty waters of the Gulf Stream. In the modern ocean, fresher water masses from the southern ocean, Antarctic Bottom Water (AABW) and Antarctic Intermediate Water (AAIW) lie below and above NADW, respectively.
How does the thermohaline circulation work?
Thermohaline circulation begins in the Earth’s polar regions. When ocean water in these areas gets very cold, sea ice forms. Surface water is pulled in to replace the sinking water, which in turn eventually becomes cold and salty enough to sink. This initiates the deep-ocean currents driving the global conveyer belt.
Where does thermohaline circulation occur?
2 days ago
The basic thermohaline circulation is one of sinking of cold water in the polar regions, chiefly in the northern North Atlantic and near Antarctica. These dense water masses spread into the full extent of the ocean and gradually upwell to feed a slow return flow to the sinking regions.
Why is NADW important?
NADW and its formation is essential to the Atlantic Meridional Overturning Circulation (AMOC), which is responsible for transporting large amounts of water, heat, salt, carbon, nutrients and other substances from the Tropical Atlantic to the Mid and High Latitude Atlantic.
How does water become anoxic?
Anoxic waters are areas of sea water, fresh water, or groundwater that are depleted of dissolved oxygen and are conditions of hypoxia. Anoxic conditions will occur if the rate of oxidation of organic matter by bacteria is greater than the supply of dissolved oxygen.
What does the NADW do?
Why is Aabw so dense?
Antarctic Bottom Water is formed around the edge of Antarctica, especially in the Ross and Weddell seas, where the formation of ice during the winter season adds salt to the water below the ice, making very dense water.
What is the meaning of thermohaline?
Definition of thermohaline : involving or dependent upon the conjoint effect of temperature and salinity thermohaline circulation in the Pacific.
Is deep water more dense?
Deep water is denser than shallow water. The water molecules are packed together more tightly because of the weight of water above pushing down.
Where is deep water in the world?
Pacific Ocean
The Mariana Trench or Marianas Trench is located in the western Pacific Ocean about 200 kilometres (124 mi) east of the Mariana Islands; it is the deepest oceanic trench on Earth.
What is NADW in the North Atlantic Ocean?
9.8.4.3 North Atlantic Deep Water NADW is the prominent layer of high salinity, high oxygen, and low nutrients between about 1500 and 3500 m depth found through the length of the Atlantic (Figures 4.11, 4.22a, bFigure 4.11Figure 4.22a, b, and 9.17).
What is the difference between NADW and AABW?
Antarctic Bottom Water (AABW), which is formed close to Antarctica, is denser than NADW, and flows northward in the Atlantic below NADW. AABW is confined to water depths below 4000 meters in the tropical and North Atlantic.
What is the temperature and salinity of the NADW?
NADW has a temperature of 2-4 °C with a salinity of 34.9-35.0 psu found at a depth between 1500 and 4000m. The NADW is a complex of several water masses formed by deep convection and also by overflow of dense water across the Greenland-Iceland-Scotland Ridge.
Is NADW the only water mass in its depth range?
NADW is not the only water mass in its depth range. The fresher CDW moves northward into the South Atlantic from the Southern Ocean, as seen in salinity on an isopycnal that lies at about 2500 m ( Figure 9.26) and the circulation at 2500 m ( Figure 9.14 a). However, NADW dominates in terms of net volume transport ( Figure 9.16 ).
