An unusual sound can be heard from space and it is coming from the most unlikely source, the Caribbean Sea.
Scientists claim that they haven't encountered anything like this before. The human ear cannot distinguish the strange sound, but its signature can be detected from space. It was the researchers from the University of Liverpool who discovered the unusual behavior in the Caribbean Sea.
"We were looking at ocean pressure through models for quite different reasons, and this region just didn't work," Chris Hughes of the University of Liverpool said in an interview with Gizmodo. "It felt like a sore thumb."
Using pressure readings from the bottom of the sea recorded from 1958 to 2013 and comparing it to NASA's Grace satellite findings, the researchers found out that the basin of the Caribbean Sea acts like a giant whistle.
"We can compare the ocean activity in the Caribbean Sea to that of a whistle," Hughes said in a statement.
"When you blow into a whistle, the jet of air becomes unstable and excites the resonant sound wave which fits into the whistle cavity. Because the whistle is open, the sound radiates out so you can hear it."
The sound is caused by large waves called Rossby wave. It travels across the ocean and disappears once it reaches the Caribbean basin. Hughes added that the strange ocean wave and the exchange of water from the ocean allow the sound or signature of the "whistle" to be observed using gravity measurements.
As to why it can be heard in space, based on the study, the whistle blows so loudly that it can be heard in space in the form of "oscillations" of the Earth's gravity field.
The "Rossby Whistle", as the researchers call it, can vary depending on some factors including sea level along the Colombian and Venezuelan coast. And understanding the behavior of the strange sounds caused by the Rossby wave might be able to help in predicting and preparing for coastal flooding in some areas near the Caribbean Sea.