sound from carbbeam heard in space

[space otter]

http://www.huffingtonpost.com/entry/caribbean-rossby-whistle_us_576b5b45e4b09926ce5dcab3
06/23/2016 04:37 am ET
Ed Mazza
Overnight Editor


There's A Mysterious Sound Coming From The Caribbean That's So Loud It Can Be Heard From Space
The "Rossby whistle" is many octaves below the range of human hearing.







In what sounds like a plot device from a science fiction movie involving sea monsters and aliens, a strange sound is coming out of the Caribbean Sea that's so loud it can be detected from space.

And it's an A-flat.

The University of Liverpool researchers who discovered the sound have dubbed it the Rossby whistle after the Rossby waves — a.k.a. "planetary waves" — that push across the ocean and cause the sound when they reach the Caribbean.

The waves often vanish at the western end of the Caribbean basin and reappear on the eastern side, a phenomena known as the Rossby wormhole.

Some waves cancel themselves out, but the bigger ones "reinforce themselves, producing an oscillation with a sharply-defined period," the university said in a news release.

"We can compare the ocean activity in the Caribbean Sea to that of a whistle," professor Chris Hughes, an expert in sea level science at the university, said in a news release.

"When you blow into a whistle, the jet of air becomes unstable and excites the resonant sound wave which fits into the whistle cavity," he said. "Because the whistle is open, the sound radiates out so you can hear it."

Like the whistle, the Caribbean Sea is partly open, which allows it to exchange water with the ocean every 120 days, producing a "whistle" so loud it can be picked up from space in the form of oscillations of the Earth's gravity field.

While the whistle itself is many octaves below the human hearing range, the researchers sped it up to make it audible, and the result can be heard in the clip above.

The visualization shown in the video also reveals what happens to the water at sea level (left) as well as pressure at the sea floor.

Besides being a curious natural phenomenon, the whistle might have some practical purpose: The researchers said they may be able to use it to predict coastal flooding.

A paper on the whistle has been accepted for publication in Geophysical Research Letters.

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http://onlinelibrary.wiley.com/doi/10.1002/2016GL069573/full

Research Letter
A Rossby Whistle: A resonant basin mode observed in the Caribbean Sea†
Authors
Chris W. Hughes,
Joanne Williams,
Angela Hibbert,
Carmen Boening,
James Oram
Accepted manuscript online: 19 June 2016Full publication history
DOI: 10.1002/2016GL069573View/save citation
Cited by: 0 articles Check for new citations
Article has an altmetric score of 155
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/2016GL069573
Abstract

We show that an important source of coastal sea level variability around the Caribbean Sea is a resonant basin mode. The mode consists of a baroclinic Rossby wave which propagates westward across the basin and is rapidly returned to the east along the southern boundary as coastal shelf-waves. Almost two wavelengths of the Rossby wave fit across the basin, and it has a period of 120 days. The porous boundary of the Caribbean Sea results in this mode exciting a mass exchange with the wider ocean, leading to a dominant mode of bottom pressure variability which is almost uniform over the Grenada, Venezuela and Colombia basins, and has a sharp spectral peak at 120 day period. As the Rossby waves have been shown to be excited by instability of the Caribbean Current, this resonant mode is dynamically equivalent to the operation of a whistle.

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