In 1960 , scientist did one of those experiments that just are n’t allowed any longer . For the sake of scientific discipline , they blew up three 3oo - lb anti - submarine turkey off the glide of Australia . A listening place 10,000 miles by in Bermuda — on the accurate other side of the planet — waited . And waited . And , about three and a half hour subsequently , they fancy the radar target that confirmed their conjecture : Yes , sound in the ocean really can travel across the reality .
Some fifty years later on , Brian Dushaw , an oceanographer at the University of Washington , has been reconstructing that 1960 experiment . His interest is not sound , however , but temperature . Sound move more quickly through warmer piss , and the speed at which sound go in 1960 is thus a snapshot of average ocean temperatures half a 100 ago . Much ocean temperature data is also of surface Ethel Waters , but the 1960 experimentation provides data for what happens about a kilometer down , in theSound Fixing and Ranging ( SOFAR ) channel .
That ’s because sounds in the sea do n’t just take a hop around willy nilly . Due to a oddity of physics , sound waves about a kilometer rich , though the exact depth varies , get trapped in the SOFAR channel : Thecompeting influences of temperature and water supply pressurekeep those waves in the zone , where sound ’s velocity is at a minimum . auditory sensation can neither easily enter nor leave the SOFAR channel , and it can travel thou and thousands of miles unattentuated . Whale song travels through the ocean in the epithelial duct . submarine go out of their way to avoid it and evade detection .
As Dushaw explained at last week’sAcoustical Society of America meetingin San Francisco , he has spend the past tenner chase down and deciphering text file to figure out the exact parameter — such as location — of the explosions in 1960 . With the help of a retired police lieutenant commander in the Australian navy , he ’s deciphered the log of the ship that fire the original shots . “ I thought they were useless at first , ” he say of the cryptic , terse ship logs . Although the ship logged its speed multiple times a day , Dushaw explained , he had to employ dead numeration to visualize out its position ; however , there is a great passel of uncertainness in the method , because deadened reckoning does not take into business relationship the wind or the current a ship is moving in .
Now that he ’s managed to reckon out an approximate locating for the ship , however , he still needs to get even more precise to learn whether ocean temperatures have switch . Dushaw is still cracking at it . For an oceanographer , he ’s having fun playing history police detective , parse through the echoes of this bomb heard around the world . [ Acoustical Society of America Meeting ]
Image : Anti - submarine turkey sink a Nazi U - Boat ; photo courtesyNational Archives
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