The Caribbean Sea is whistling. You just can't hear it

A whistle is making waves in the scientific community. Or, rather, a wave is making whistles. 

Scientists at the University of Liverpool say they've discovered a sound emanating from the basin of the Caribbean Sea. They call it the Rossby Whistle and it sounds like this:

As It Happens0:13Listen to the Rossby Whistle

Scientists have discovered that the Carribean Sea functions just like a whistle, emitting a sound that can be detected from space

Joanne Williams is one of the researchers at the university who discovered that sound. She explains to As it Happens host Carol Off what's behind it.

"[It's] the sound of a wave moving across the Caribbean Sea. But it's being speeded up by a factor of 30 times. So it's 30 octaves higher than the real thing," she says.

And that's why, says Williams, you wouldn't be able to detect it if you were out floating on the Caribbean Sea.

"You wouldn't notice it. You'd only see it if you looked at the long-term records," she explains. That's because each wave takes about 120 days to cross the sea. "And it's about 1,000 kilometres," says Williams.

That, of course, raises the question as to how Williams and her team were able to determine that the waves are in fact emitting a sound.

If you think of it as an organ pipe — imagine a pipe that you blow down — and then there's a current going through the sea and it's just like you blowing down that pipe.- Joanne Williams, researcher, University of Liverpool

"We've looked at the satellite records of the sea height — the sea level — and you can see it going up and down. You can see that wave in the sea level. And we've also seen it from a pressure recorder that's at the bottom of the sea. And also in ocean models. So you take the wave from the data and you speed the information up and turn it into a wave file directly."

Williams describes how the wave's particular resonance is produced.

"If you think of it as an organ pipe — imagine a pipe that you blow down — and then there's a current going through the sea and it's just like you blowing down that pipe," she says.

The name Rossby refers to the particular type of wave that is often detected on the open sea, says Williams. Williams says studying the wave is a useful indicator for future ocean trends, largely because of its predictability.