Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Internal waves appear to have the muscle to pump up mid-lats

25.06.2003


When internal waves up to 300 feet first form they cause a mighty churning of ocean waters – something invisible to and unfelt by anyone at the surface.


Maps, the first of their kind, show energy of internal waves carried away from where they originated. The larger and longer the arrows (vectors) the more energy is being carried away from where the waves originated. The upper map shows that, in general, internal waves generated by storms move through the ocean depths toward the mid-latitudes. The lower maps shows energy moving directly away from places where tidal forces have created internal waves.Graphic credit required: University of Washington/Nature



Now in a novel use of mooring data, some of it three decades old, a University of Washington researcher has calculated just how much punch these waves appear to carry as they travel, or propagate, thousands of miles from where they originate.

It’s energy that appears to be crucial to the conveyor-belt-like circulation wherein millions of cubic meters of icy-cold water sink each second at high latitudes and are driven to upwell at lower latitudes. Without such upwelling, global ocean circulation would stall, causing the entire ocean to fill with cold water. Further, nutrients that have drifted down to the ocean depths would remain in the deep instead of being carried back to surface waters for use by plankton, the tiny plants and animals on which all other marine life depend and which greatly affect how much carbon dioxide is absorbed and released by the oceans.


Internal waves are just like waves one sees breaking on beaches except they occur completely below the surface. For the most energetic such waves, which get started either during stormy weather or when tides pull water across especially rough places on the seafloor, up to 50 percent of their original energy can be carried far away as the waves undulate through the ocean depths, according to Matthew Alford, an oceanographer with the University of Washington’s Applied Physics Laboratory.

That’s important because climate modelers need to know all the key factors that affect ocean mixing that occurs at mid-latitudes. Previous measurements and calculations by Alford, and by National Aeronautics and Space Administration and Oregon State University scientists, show that internal waves have the 2 trillion watts that would account for such ocean mixing.

Alford provides the first glimpse of how much of that energy actually makes it very far from where the waves originate.

"The fluxes . . . are large enough to transport, across ocean basins, globally significant amounts of energy available for mixing," Alford wrote in the journal Nature last month. "Global mapping of their fluxes is an important step in determining how and where internal-wave mixing is accomplished."

Alford, an Office of Naval Research Young Investigator, combed historical data from more than 1,000 moorings – some used for projects as far back as 1973. Sixty had instruments at the right depths and collected data for long enough, at least a winter, for Alford’s purposes. Moorings provide fair coverage of ocean waters in the North Atlantic and Pacific but very poor coverage in low latitudes in the Southern Hemisphere, he says, something that could be considerably improved by deploying several well-placed moorings in the future.

He found that the kind of internal waves caused by tidal forces pulling water across underwater ridges, shoals, channels and other rough places on the seafloor, for example around the Hawaiian Islands, carry 30 percent to 50 percent of their energy directly away from their sources, a process that goes on year-round.

A second type of internal waves, one caused by sudden wind events and storms, appear to carry at least 15 percent to 20 percent of the energy input from where they originate, mainly during the stormy months of winter, and that energy is usually directed toward mid-latitudes areas. Alford says the focus in recent years has been on the importance of internal waves generated by internal tides, whereas his work suggests that internal waves generated by winds are just as significant.


###
For more information: Alford, 206-221-3257, malford@apl.washington.edu

Sandra Hines | EurekAlert!
Further information:
http://www.washington.edu/

More articles from Earth Sciences:

nachricht Filling the gap: High-latitude volcanic eruptions also have global impact
20.11.2017 | Institute of Atmospheric Physics, Chinese Academy of Sciences

nachricht Antarctic landscape insights keep ice loss forecasts on the radar
20.11.2017 | University of Edinburgh

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Previous evidence of water on mars now identified as grainflows

21.11.2017 | Physics and Astronomy

NASA's James Webb Space Telescope completes final cryogenic testing

21.11.2017 | Physics and Astronomy

New catalyst controls activation of a carbon-hydrogen bond

21.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>