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Earth Math Science

Walter Munk's Astonishing Wave-Tracking Experiment 55

An anonymous reader writes in with a look at a scientist's interesting wave-tracking experiment and the incredible journeys that waves make. His name is Walter Munk, now in his 90s and a professor emeritus at the Scripps Institution of Oceanography in La Jolla, California. About 60 years ago, he was anchored off Guadalupe Island, on Mexico's west coast, watching swells come in, and using an equation that he and others had devised to plot a wave's trajectory backward in time, he plotted the probable origins of those swells. But the answer he got was so startling, so over-the-top improbable, that he thought, "No, there must be something wrong." His equations said that the swells hitting beaches In Mexico began some 9,000 miles away — somewhere in the southern reaches of the Indian Ocean, near Antarctica. "Could it be?" he wrote in an autobiographical sketch. Could a storm half way across the world produce a patch of moving water that traveled from near the South Pole, up past Australia, then past New Zealand, then across the vast expanse of the Pacific, arriving still intact – at a beach off Mexico? He decided to find out for himself. That is why, in 1957, Walter Munk designed a global, real life, wave-watching experiment.
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Walter Munk's Astonishing Wave-Tracking Experiment

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  • by Sasayaki ( 1096761 ) on Monday July 14, 2014 @02:13AM (#47446883)

    ... making waves.

    • That's a swell joke.
  • Slow news day? (Score:2, Informative)

    by pipatron ( 966506 )
    What kind of non-story is that? One link points to some guy writing about how some other guys went to study waves at different locations. It doesn't say anything about how they did it, or has any technical information. The other link is a PDF scanned from a paper from 1982. Slow day when you have 32 year old news?
  • Cheap documentary? (Score:5, Interesting)

    by jandersen ( 462034 ) on Monday July 14, 2014 @05:44AM (#47447289)

    Could a storm half way across the world produce a patch of moving water that traveled from near the South Pole

    This reads like the voice-over for one of those embarrassingly poor 'documentaries' you sometimes see, where the producers have tried to sensationalize a fairly standard, scientific subject, and draw it out to fill a whole hour, when it could have been adequately explained in about 10 minutes. A shame, really, because the subject is in fact quite interesting.

    However: waves don't move patches of water half-way around the globe; the actual water more or less stays in place. A wave is simply energy propagating through a medium, and it is quite astonishing to hear that an ocean wave can travel that far without dissipating, because the expectation is that it would spread out in a circular pattern and thus grow weaker with distance. I would have been interested in hearing what the explanation is.

    • Re: (Score:3, Informative)

      by Anonymous Coward

      In a plane you are correct - they spread and dissipate.

      The earth is not a plane - and the curvature will focus the wave after a certain distance is traveled.

      • by Anonymous Coward on Monday July 14, 2014 @07:33AM (#47447575)

        After 1/4 of the Earth's circumference (6000 miles) the wavefront stops dissipating and starts converging.

        • by jfengel ( 409917 )

          Have you got a link with more information? (I did try Googling, but words like "wave" and "sphere" and "converge" are used in too many contexts and they drown out specifics.) How does that work?

          • by the_other_chewey ( 1119125 ) on Monday July 14, 2014 @02:33PM (#47450255)
            Just simple geometry:

            Imagine a planet completely covered with water. Now throw in a big stone at one of the poles:
            This results in a circular wave expanding from the pole, parallel to the latitudes.
            As soon as it crosses the equator, it starts converging again, until it arrives as a peak at the
            opposite pole.

            Distance from pole to equator: circumference/4.

            This works with a stone drop at any other point on the globe as well, I just used poles and
            equator because it's easier to imagine. In reality, land masses complicate things a bit of course.
      • Speaking of planes, could this help us find Malaysian Air 370?
    • by tomhath ( 637240 )

      waves don't move patches of water half-way around the globe

      I suppose it depends on what you mean by "move". The swell (which is different from a wave of water) is moving the water vertically, and the swell did originate thousands of miles away.

    • by mikael ( 484 )

      Look at what happens when an earthquakes occurs in one side of the Pacific, creating a tsunami which travels all the way across the ocean. With a storm over the ocean, the waves can reach 100 meters or more in height, and stretch for hundreds of meters (determined by a mathematical equation linking amplitude to wavelength and ocean floor depth). And the storm is 100 miles across.

  • by Anonymous Coward

    I'm glad this was posted, at least for me. I had the pleasure of meeting him some years ago. I also worked for a scientist who had been a student of his for many years. Munk contributed greatly to the understanding of ocean waves.

  • What's amazing is that the "paper" was a celebration of Monk's already interesting career ... upon his supposed retirement age at 65. So yes for those who critiqued this as a slow news day, and yes for an old paper, and yes for perhaps obvious news. But how about a celebration of the life of this man, this person, who kept going, starting at 65! I for one hope I could be some small percentage as 'meaningful' for me when I reach the 65 through 95 range!

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