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Very interesting: Underwater 'Rivers' Discovered on Ocean Floor.

Quote:An underwater "river" has been discovered snaking along the ocean bed off southwestern Australia.

The undersea phenomenon — layers of dense water that creep along the ocean floor at a rate of about a half-mile (1 km) a day — was found to be some 65 feet (20 meters) thick and stretches for more than 60 miles (100 kilometers).

Researchers say it's the first time these rivers have been glimpsed in such warm waters.

"These dense shelf water cascades are common in high-latitude regions as a result of ice formation, but this is the first time these processes have been discovered in sub-tropical regions, and to be present throughout the year," said the University of Western Australia's Chari Pattiaratchi in a statement.

Water evaporation during the region's summers, followed by cooling during the winters, fuels the formation of the rivers, Pattiaratchi said, leading to the gathering of high-density waters in the coastal shallows, which then flow offshore as slow-moving rivers.

So-called underwater rivers have been discovered in different spots around the globe.

In the Black Sea, researchers uncovered an underwater river, but one that cut deep into the seafloor, much as rivers on dry ground wind through a landscape.

The Australian underwater river was uncovered by seafaring gliders, self-propelling robots equipped with sensors to detect water temperature, salinity, plankton productivity, turbidity and dissolved oxygen. They can operate nonstop in the water for up to eight months.

The finding is published in the journal Geophysical Research Letters.
This just goes to show how much information is lacking about deep ocean currents which have a strong effect on heat energy transport around the globe.

Link:
http://science.nasa.gov/science-news/sci...veyorbelt/

(06-10-2011, 06:05 PM)jt Wrote: [ -> ]This just goes to show how much information is lacking about deep ocean currents which have a strong effect on heat energy transport around the globe.

Link:
http://science.nasa.gov/science-news/sci...veyorbelt/

You know, one thing that wasn't mentioned was whether or not the colder undercurrent was fresh water, or saline solution. I realize that all things being equal, the fresh water is lighter and would be on top. But if it is a great deal cooler, does that give it enough mass to be heavier than the warm salt water?

I wish the article was more in depth. Or perhaps I overlooked something?

Saline water is more dense than cold water: 1.025 g/ml vs 1.00 gm/ml. The density of water does not change much with temperature (unless it gets very hot), and is always below 1.025 gm/ml.

http://en.wikipedia.org/wiki/Seawater
(06-14-2011, 05:38 PM)jt Wrote: [ -> ]Saline water is more dense than cold water: 1.025 g/ml vs 1.00 gm/ml. The density of water does not change much with temperature (unless it gets very hot), and is always below 1.025 gm/ml.

http://en.wikipedia.org/wiki/Seawater

Ok, I can see this. But how does the Atlantic Ocean Conveyor work when it moves upward in the North Atlantic. As it moves further north, it comes in contact with melting ice which adds colder, fresh water into the ocean. As it gets colder, and less salty, it drops to the ocean floor, and begins the long journey back south, where it continues around the cape and into the Indian ocean.

[Image: 800px-Thermohaline_Circulation_2.png]

because nobody said your underwater rivers are freshwater rivers. the few drops added by glaciers don't matter in the enormous volume of the gulf stream. it cools down up north, and that makes it sink. the gulf stream is driven by the winds.
I think there is some controversy over whether salinity or temperature drives the thermohaline circulation. I think that Q has the right idea, namely that the coldness of the glacial melt, when mixed with saline waters drives the cold, slightly less saline waters downward.
it's solely the winds. the term thermohaline is missleading because thermo doesn't drive the circulation.
The winds clearly drive surface currents. However the deep sea currents are quite remote from the surface. The gravitational effects of density must play a role.