Interesting! "Cyclone of the deep sits off Sydney"

Discussion in 'Alpine & Southern' started by white_beanie, Mar 14, 2007.

  1. white_beanie

    white_beanie Part of the Furniture

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    http://www.smh.com.au/news/national/cycl...3722538038.html

    Cyclone of the deep sits off Sydney
    David Braithwaite
    March 14, 2007 - 3:14PM

    The marine equivalent of a cyclone is sitting off Sydney's coast, causing a massive whirlpool which is turning the ocean green and spewing chilly water towards beaches.

    A 200 kilometre-wide cyclonic eddy has pulled the sea's surface down by 70 centimetres and sucked cold deep ocean water onto Australia's eastern continental shelf.

    The whirlpool is 1000 metres deep, reaching the ocean floor, CSIRO oceanographers say.

    The centre is 100 kilometres off the coast and could stay there for several months.

    Satellites can measure the drop in ocean surface caused by the eddy's pull, clearly showing how it is pushing aside the powerful East Australian Current running off our coast.

    Another eddy of similar proportions is sitting further off the coast.

    The eddies were like underwater cyclones, and the latitude of the coast near Sydney put it right in the marine cyclone belt, CSIRO oceanographer Dr David Griffin said.

    "This eddy is a particularly strong one - it's caused cold water to slop up onto the continental shelf and in places that water's available to come to the surface," he said.

    "It's not happening right now off Sydney, but earlier this summer people will recall very cold beach temperatures - that was associated with the early phase of this eddy.

    "It doesn't seem to be impacting beach temperatures at the moment, but that doesn't mean it won't happen again."

    A run of warm water temperatures last September was due to an eddy spinning the other way, Dr Griffin said.

    He said the current cyclonic eddy could chill water at the edge of the continental shelf from 18 degrees to 14 degrees.

    "It has a big impact on ocean ecology - the cold water coming up has a lot of nutrients and when that's combined with sun, the phytoplankton grows like crazy," he said.

    "That's why the water goes green, you can see that from a boat."
     
    #1 white_beanie, Mar 14, 2007
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  2. Mrstr_Chief

    Mrstr_Chief One of Us

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    That explains a lot. Hope it doesnt happen this w/e, wanting to go to the beach [​IMG]
     
    #2 Mrstr_Chief, Mar 14, 2007
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  3. thermalben

    thermalben Hard Yards

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    [apologies - I posted on this topic in another forum, and have copied it here]

    This is just a bit of media hype - eddies are relatively common in the Tasman Sea. They've used the term "mysterious whirlpool", as it grabs your attention a lot more than "eddy", and the phrase "sea surface to fall by almost a metre", before clarifying the actual figure as being 70cm. Although that sounds like a wet speed hump, you have to remember that this drop of 70cm is actually spaced over a hundred kilometers or so, and is not noticeable by passing vessels.
     
  4. trappers

    trappers Safety not guaranteed Moderator Ski Pass: Gold

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    #4 trappers, Mar 14, 2007
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  5. white_beanie

    white_beanie Part of the Furniture

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    I think it's interesting because it's the first time I've noticed such cool water at the beach in summer, and I didn't know why.
     
  6. trappers

    trappers Safety not guaranteed Moderator Ski Pass: Gold

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    yeah but what we are saying is that this is not exactly an unusual occurance, it happens quite often. If the media presented it as an educational rather than sensationalist article, then perhaps we wouldn't care ...
     
  7. white_beanie

    white_beanie Part of the Furniture

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    tough crowd [​IMG]
     
    #7 white_beanie, Mar 15, 2007
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  8. phantomas

    phantomas Hard Yards

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    this one is fantastic, you can see Kelvin-Hemlholtz instability in the EAC just off Byron, and the way that nasty Seal Rocks prevents the warm water coming to Sydney [​IMG]

    [​IMG]
     
    #8 phantomas, Mar 15, 2007
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  9. filski

    filski Old n' Crusty Ski Pass: Gold

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    While it's true that eddies area common feature of the ocean, the strength of this one is not. Ocean eddies featured in the mission profile of Australia's first astronaught - Paul Scully-Power who returned with some fantastic images only visible from space. I have his book in storage in Brissy.

    Now with all this cold water coming to the surface, where is the warm water going?

    Latest
    [​IMG]
     
    #9 filski, Mar 16, 2007
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  10. filski

    filski Old n' Crusty Ski Pass: Gold

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    [​IMG]
     
    #10 filski, Mar 16, 2007
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