NASA: The Thermohaline Circulation (The Great Ocean Conveyor Belt) [720p]

The oceans are mostly composed of warm salty water near the surface over cold, less salty water in the ocean depths. These two regions don't mix except in certain special areas. The ocean currents, the movement of the ocean in the surface layer, are driven mostly by the wind. In certain areas near the polar oceans, the colder surface water also gets saltier due to evaporation or sea ice formation. In these regions, the surface water becomes dense enough to sink to the ocean depths. This pumping of surface water into the deep ocean forces the deep water to move horizontally until it can find an area on the world where it can rise back to the surface and close the current loop. This usually occurs in the equatorial ocean, mostly in the Pacific and Indian Oceans. This very large, slow current is called the thermohaline circulation because it is caused by temperature and salinity (haline) variations.
This animation shows one of the major regions where this pumping occurs, the North Atlantic Ocean around Greenland, Iceland, and the North Sea. The surface ocean current brings new water to this region from the South Atlantic via the Gulf Stream and the water returns to the South Atlantic via the North Atlantic Deep Water current. The continual influx of warm water into the North Atlantic polar ocean keeps the regions around Iceland and southern Greenland mostly free of sea ice year round.

The animation also shows another feature of the global ocean circulation: the Antarctic Circumpolar Current. The region around latitude 60 south is the the only part of the Earth where the ocean can flow all the way around the world with no land in the way. As a result, both the surface and deep waters flow from west to east around Antarctica. This circumpolar motion links the world's oceans and allows the deep water circulation from the Atlantic to rise in the Indian and Pacific Oceans and the surface circulation to close with the northward flow in the Atlantic.

The color on the world's ocean's at the beginning of this animation represents surface water density, with dark regions being most dense and light regions being least dense (see the animation Sea Surface Temperature, Salinity and Density). The depths of the oceans are highly exaggerated to better illustrate the differences between the surface flows and deep water flows. The actual flows in this model are based on current theories of the thermohaline circulation rather than actual data. The thermohaline circulation is a very slow moving current that can be difficult to distinguish from general ocean circulation. Therefore, it is difficult to measure or simulate.

This animation first depicts thermohaline surface flows over surface density, and illustrates the sinking of water in the dense ocean near Iceland and Greenland. The surface of the ocean then fades away and the animation pulls back to show the global thermohaline circulation.

credit: NASA/Goddard Space Flight Center/UMBC

source: http://svs.gsfc.nasa.gov/goto?3658

Category:

Education

Tags:

• NASA
• thermohaline circulation
• ocean currents

[exarkunrocks]

why do the arrows look like racing sperm cells to me...? i can't be the only one that saw that

[djxatlanta]

@exarkunrocks - I think you may be the only one... ;-)  Now if the arrow tails had a helical motion to them, then I would say yes, they would be sperm-like. ;-)

[lilaclila90]

how much time taken by the arrow(flow of water), to reach the same point, after it circulate in this great conveyor belt?

[djxatlanta]

@lilaclila90 - the answer to your question is in the second-to-last paragraph. =)

[88blockNS]

I've got a question. If you went far enough down into the ocean, would the current be visible? Like in the movie Finding Nemo? If so, is there any video footage?

[djxatlanta]

@88blockNS - I can't recall if I've seen videos of current, but I suggest doing a search on YouTube for something similar -- "brine pools" -- they are ponds of water discovered at the bottom of the ocean with a high salinity content that have their own flat surfaces and waves.

[findlesx]

The description is incorrect

The water in the depths is more salty, due to the arctic sea ice... Thats how the water drops and becomes cold etc etc...

[engelmohr2006]

incredible and this is what manipulates and controls our weather climate system awesome

[lilaclila90]

@djxatlanta thank you. =)

[gamble2611]

@Thepoliticman The closest thing to the current in Nemo would have been one of the narrow fast flowing western boundary currents, like the Gulf stream or Kuroshio current. The deep water circulation is far slower than these. Besides... its a kids film, not a science documentary, the factual correctness wouldn't have been their top priority...

[phpfanboi]

So how long until Japans nuclear waste is carried around the world? I can't believe how catastrophic it is , for such a high technological country i definitely thought there would be fail safe plans for these types of natural disasters involving nuclear powered systems.

[MightyTheMonkey]

school

[HostileNegotiator]

@djxatlanta The science in the description is correct :)