Waves breaking over sandy beaches are captured in countless tourist photos. But enormous waves breaking deep in the ocean are seldom seen, although they play a crucial role in long-term climate cycles.
A University of Washington study for the first time recorded such a wave breaking in a key bottleneck for circulation in the world's largest ocean. The study was published online this month in the journal Geophysical Research Letters.
The deep ocean is thought of as dark, cold and still. While this is mostly true, huge waves form between layers of water of different density. These skyscraper-tall waves transport heat, energy, carbon and nutrients around the globe. Where and how they break is important for the planet's climate.
"Climate models are really sensitive not only to how much turbulence there is in the deep ocean, but to where it is," said lead author Matthew Alford, an oceanographer in the UW Applied Physics Laboratory. He led the expedition to the Samoan Passage, a narrow channel in the South Pacific Ocean that funnels water flowing from Antarctica.
"The primary importance of understanding deep-ocean turbulence is to get the climate models right on long timescales," Alford said.
Dense water in Antarctica sinks to the deep Pacific, where it eventually surges through a 25-mile gap in the submarine landscape northeast of Samoa.
"Basically the entire South Pacific flow is blocked by this huge submarine ridge," Alford 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."
In the 1990s a major expedition measured these currents through the Samoan Passage. The scientists inferred that a lot of mixing must also happen there, but couldn't measure it.
In the summer of 2012 the UW team embarked on a seven-week cruise to track the 800-foot-high waves that form atop the flow, 3 mile
|Contact: Hannah Hickey|
University of Washington