An ultimate wave has been found in the Pacific, but it’s at the bottom of the ocean. For the first time, waves that crash through a choke point called the Samoan Passage have been measured by University of Washington scientists.
Dense Antarctic bottom water is a key driver of global ocean circulation, and as it forces its way north it funnels into this passage deep below the Pacific Ocean’s surface, oceanographer Matthew Alford says.
”Basically, the entire South Pacific flow is blocked by this huge submarine ridge,” he said.
”The amount of water that’s trying to get northward through this gap is just tremendous – 6 million cubic meters of water per second, or about 35 Amazon Rivers.”
And just like a wave on a beach or a point, water rises and collapses. As it rushes through, the ridge forms a lee, the water becomes unstable and turbulent, and breaks.
Professor Alford’s team found the phenomenon when they lowered instruments five kilometres under the surface at the passage, just north of the Samoan islands, about 4500 kilometres north-east of Brisbane, in a 2012 expedition.
He said in a study published in the journal Geophysical Research Letters last week that the passage’s breaking waves mixed water at a rate up to 10,000 times greater than surrounding slow-moving water.
”We found there’s loads and loads of turbulence in the Samoan Passage, and detailed measurements show it’s due to breaking waves,” he said.
Professor Alford’s WaveChasers group has sailed the world to measure undersea waves, which he said travel across oceans, and were powerful enough to force submarines to hit the bottom or breach the surface.
As prime mixers of seawater around the planet, they also had a strong influence on climate, Professor Alford said.
Having broken through the Samoan Passage, the Antarctic water mixed with warmer upper layers and disappeared.
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