Giant Internal Waves Caught Breaking

"This is the first effort to look in the ocean for the theoretical breakdown in the internal wave," said internal wave researcher John Toole of Woods Hole Oceanographic Institution, who was not a member of the expedition.

Once the data were in, they revealed the internal waves moving along north. But instead of fully breaking, the data showed the waves only "sloshed over" a bit, said Alford, conserving most of their energy.

"The rest is just rocketing off to parts unknown," said Alford. Perhaps they break closer to the Aleutians or even on the Oregon coast, he said. Their findings were published in the current issue of the journal Geophysical Research Letters.

Discovering where the tidally-induced internal waves break is especially important for accurately tracking how oceans move heat and energy around the planet. It's thought that internal waves play a big role in allowing cold, deep waters to well up to the surface in lower latitudes.

Those upwellings are part of a global heat conveyor belt known as the thermo-haline circulation which carries warmer saltier waters like the Gulf Stream poleward to cool and sink. Then the waters move along the bottom of the oceans to lower latitudes where the waters then rise -- if there are internal waves in the right places to mix things up and help push the cold waters upward.

"The real key is not only how much turbulence, but where the turbulence is," said Alford. His team's work is the first step in that deep-sea search.

Related Links:

Larry O'Hanlon's blog: Earth Matters

University of Washington, Seattle, School of Oceanography

Woods Hole Oceanographic Institution

NASA: The Water Cycle