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Blobrana


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Gigantic ocean waves
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Gigantic ocean waves, spanning hundreds of kilometres from crest to crest, have been speeding up thanks to global warming, a new model suggests.
Geophysicists predict that as the ocean surface warms, these so-called planetary waves should speed up. To test this idea, John Fyfe and Oleg Saenko at the University of Victoria in British Columbia, Canada, modelled the changes to ocean wave patterns over the 20th and 21st centuries.

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Blobrana


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RE: Giant freak waves
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Huge waves that struck Reunion Island and coastlines across Indonesia earlier this month all originated from the same storm that occurred south of Cape Town, South Africa, and were tracked across the entire Indian Ocean for some 10 000 kilometres over a nine-day period by ESAs Envisat satellite.
 Waves reaching up to 11 metres devastated Frances Reunion Island in the Indian Ocean when it slammed into the southern port of Saint Pierre on 12 May. Six days later waves created from the same storm measuring as high as seven metres began crashing into Indonesia coastlines from Sumatra to Bali, killing at least one person and causing some 1200 people to flee their homes.

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Blobrana


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Posts: 131433
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Reunion Island freak waves
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The origin and movement of waves reaching up to 11 metres that devastated Frances Reunion Island in the Indian Ocean on Saturday evening have been detected with ESAs Envisat satellite.
The waves that thrashed the southern port of Saint Pierre, leaving two fishermen missing, causing several piers to collapse and flooding several homes and businesses, originated south of Cape Town, South Africa, and travelled northeast for nearly 4000 km over a period of three days before slamming into Reunion Island.

Image7
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Credits: IFREMER - BOOST Technologies

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-- Edited by Blobrana at 13:19, 2007-05-16

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Blobrana


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RE: Giant freak waves
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Once, they were regarded as maritime myth and legend. Freak waves that rose 30m from the ocean and snapped ships in half were given as much credence by scientists as the existence of mermaids.

Now it seems the fantastic accounts by sailors through the ages might have been more than just tales of the deep. Research suggests up to 10 gigantic "rogue waves" - some as tall as a 10-storey building - are likely to be crashing through the world's oceans at any given moment.

Dr Wolfgang Rosenthal, who helped the European Space Agency pioneer a study using satellite surveillance, said: "Two large ships sink every week on average. But the cause is never studied to the same detail as an air crash. It simply gets put down to 'bad weather'."

The information has come from a project launched six years ago. Earth-scanning satellites used radar to monitor the oceans and the data was analysed. It revealed 10 massive waves, some of them taller than the combined height of eight double-decker buses. Further research produced an atlas of freak wave events.

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Blobrana


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When seafarers described giant freak waves in tones of awe, sceptical landlubbers dismissed them as fantasy. Now scientists believe they have evidence of a wave the size of a 10-storey building.

It happened on September 16 last year when Hurricane Ivan stormed across the Gulf of Mexico and tore into the coast of Alabama, accompanied by 210km/h winds and storm surges more than 2m high.
While still out at sea, oceanographers report, the hurricane also produced a series of giant waves, one of which stood 28m from crest to trough, a new world record for a wave.
But science, like old salts' tales, is fallible. The seabed instruments that measured the surge were turned off at the moment the winds reached their peak, and scientists from the Naval Research Laboratory at Stennis Space Centre, Mississippi, had to employ a computer model to predict that, while they were not looking, at the height of the storm the wave reached 40m.
By comparison, the tsunami that swept across the Indian Ocean in December stood about 9m high as it hit shorelines, although in some parts of Indonesia it was reported to have reached 20m.

The greatest wave of all is not yet upon us.
Scientists predict that if a future volcanic eruption sends a large part of the island of La Palma in the Canaries into the sea, it could cause a wall of water 900m high.
Reassuringly, they do not expect it this century.

The previous record for a wave was 26m, measured by the ocean weather ship Weather Reporter in the Atlantic on December 30, 1972.

Giant waves are difficult to record because buoys on the surface of the sea are usually wrecked by the intense storms.
Luckily, the eye of Hurricane Ivan passed over 14 water pressure sensors spread over 61km of seafloor 160km off the Alabama coast.
The sea currents generated by the hurricane broke another world record: the maximum current on the sea floor was 2.25m/s compared with the Gulf Stream, which reaches top speeds of about 1.5m/s.

The hurricane caused the deaths of 116 people across the Caribbean.

The Times



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