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     Underwater-submerged trans-Atlantic island chains | [q] 2015-03-20 18:46
KRSplatinumavatar
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Posts: 259
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Recently I have been saying that it's possible there are underwater submerged island chains in the Atlantic Ocean between the western Sahara and eastern United States coastal areas. I suspected that these hypothetical island chains, centuries ago, were once above water during an era where the sea level was lower, and could have been used for human migration between the Americas and the Eurasia-Africa regions. Some test evidence has been linked to this concept:

http://www.sciencemag.org/content/347/6228/1297.summary

Quote:
Science 20 March 2015:
Vol. 347 no. 6228 pp. 1297-1298
DOI: 10.1126/science.347.6228.1297

In Depth

Oceanography
New satellite radar could find 100,000 underwater mountains

Eric Hand

With only about 10% of the sea floor mapped with high-resolution sonar from ships, scientists assembling global maps have to rely on an indirect method: using orbiting radar satellites to trace subtle bumps and depressions in the water surface, which mirror the shape
of the sea floor. Even the most advanced map made by that technique has trouble identifying and locating seamounts less than 2 kilometers tall. But a new study demonstrates how a French radar instrument on an Indian satellite could greatly enhance seamount maps, putting submariners on safer courses while helping with climate science, fisheries science, and tsunami forecasts. Tests in the Pacific Ocean showed that the instrument, a radar altimeter called AltiKa, can spot seamounts as small as 1 kilometer tall. Researchers say it could boost the number of known seamounts from 10,000 to 100,000.


My initial suspicions were derived not just from folklore, but from observation of Earth view in Google maps, consistently showing underwater formations off the coast of the western Sahara region, as well as in the Caribbean Sea.

https://www.google.com/maps/@32.8983818,-42.8188983,3696695m/data=!3m1!1e3

At the above link, it's easy to see what I mean. Look between the Bermuda, Long Island and Caribbean islands to the west, versus the Canary Islands to the east side of the map. Note as well the Azores archipelago volcanic islands, which are more-so in the middle of the northern Atlantic ocean.

Personally, I'm not trying to prove or disprove anything - I just want to bring up the topic for discussion. Hopefully more groundbreaking research can allow this line of study to continue into further development. All ideas are welcome and appreciated, in my book!

EDIT: Ok, here's the full text of the above article - if this violates my subscription access permissions to Science magazine, that's fine it should be easy to remove from this post if needed.

Quote:
Science 20 March 2015:
Vol. 347 no. 6228 pp. 1297-1298
DOI: 10.1126/science.347.6228.1297
IN DEPTH
OCEANOGRAPHY
New satellite radar could find 100,000 underwater mountains
Eric Hand
The submarine never saw it coming. In 2005, the nuclear-powered USS San Francisco crashed into an undersea extinct volcano, known as a seamount, in the western Pacific Ocean, killing one crew member and crippling the vessel. Although the sub returned to dock in Guam and a larger disaster was averted, the accident underscores one of marine geologists' biggest complaints: Earth's oceans are still mostly aqua incognita.


...


Bulge marks the spot
Extra gravity due to the mass of a seamount creates a bulge of water that can be measured from space.
ILLUSTRATION: ADAPTED FROM WESSEL ET AL., OCEANOGRAPHY BY G. GRULLÓN/SCIENCE

...

Quote:

With only about 10% of the sea floor mapped with high-resolution sonar from ships, scientists assembling global maps have to rely on an indirect method: using orbiting radar satellites to trace subtle bumps and depressions in the water surface, which mirror the shape of the sea floor. Even the most advanced map, published in Science last October (Science, 3 October 2014, p. 65), has trouble identifying and locating seamounts less than 2 kilometers tall. But now, a new study demonstrates how a French radar instrument on an Indian satellite could greatly enhance seamount maps, putting submariners on safer courses while helping with climate science, fisheries science, and tsunami forecasts.

The French radar instrument, called AltiKa, could boost the number of known seamounts from 10,000 to 100,000, says Walter Smith, a marine geophysicist at the National Oceanic and Atmospheric Administration in College Park, Maryland. “We're going to find more of them with AltiKa than we've found before,” he says. “How many there are that are waiting to be discovered is an open question.”

AltiKa, on the Indian SARAL satellite that launched in 2013, is a radar altimeter that measures the height of the ocean surface. The instrument primarily serves climate researchers, who want to track sea-level rise. But like other satellite radar altimeters, it can also detect the subtle bulge of water that gathers over a seamount, because of the slightly enhanced gravity at that spot. By subtracting the effects of tides and weather on the shape of the water surface, scientists can nail down the gravity signal, and hence a seamount's height and shape. Unlike most other satellite radars, which rely on the Ku radar band, AltiKa scans the sea with a Ka-band radar, which emits shorter wavelengths—yielding a smaller footprint and a faster sampling rate. At three spots in the Pacific Ocean, Smith showed, AltiKa can spot seamounts as small as 1 kilometer tall.

Smith's results were published online on 12 March in Marine Geodesy in advance of a special issue on the AltiKa instrument. Paul Wessel, a marine geophysicist at the University of Hawaii, Manoa, says the study is a good proof of principle showing how AltiKa can enable marine geologists to see more clearly. “It pushes the envelope a bit further,” he says.

The scientific payoff extends beyond submarine navigation. For example, tsunami waves are sensitive to the roughness on the ocean floor; seamounts slow a passing tsunami, bending and deflecting its energy. A better map would improve tsunami predictions. Also sensitive to seafloor roughness are the internal waves in oceans that bring up deep, cold, nutrient-rich waters to the surface and carry dissolved atmospheric carbon dioxide to ocean depths. “Knowing the seafloor bathymetry better would definitely improve the mixing models that we use,” says Steven Jayne, a physical oceanographer at Woods Hole Oceanographic Institution in Massachusetts.

Seamounts are also important for ecology, because they provide a rich habitat for many species, sustained by the nutrient-rich deep waters that well up near seamounts. One drawback to a more refined map, says Peter Auster, an ecologist at the Mystic Aquarium in Connecticut, is that it could aid certain destructive commercial fishing operations, which have been known to target seamounts and quickly strip them of fish. On the flip side, Auster says, a more complete map could help ecologists piece together evolutionary patterns of biogeography: how related species leaped from one underwater island to another.

For now, AltiKa traces out the same narrow tracks across the ocean, orbit upon orbit, rather than varying its course to achieve global mapping coverage. Smith hopes that as SARAL approaches the end of its mission lifetime in a few years, project managers will allow the satellite to drift into a mapping orbit. He notes that that same decision was eventually made for the satellites Jason and CryoSat-2—and the resulting gravity data helped create the map published in Science last year. “Until they do that,” Wessel says, “you're only going to get good data on small strips.”

AltiKa's principal investigator, Jacques Verron, of the Laboratory of Geophysical and Industrial Flows in Grenoble, France, says India and France have not seriously discussed changing the satellite's orbit to make the global gravity map, but he plans to raise the issue at future meetings with India's space agency.


Actually, a good example of what I mean is - New England seamount chain (off the coast of Massachusetts). Look below at a bathymetric map:

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