"Mysterious whistle" like noise from Caribbean Sea- So Powerful that it can be heard from Space

Ocean scientists at the University of London detected a strange whistle like sound coming from the depth of Caribbean Sea which blows so loudly that it can be heard from space.

Caribbean Sea covers an area over 1 million square miles is a part of the Atlantic Ocean, southeast of the Gulf of Mexico and is bounded by South America, Central America and the Caribbean islands.

  (Image Courtesy:NASA Goddard Space Flight Centre/Flickr)

The whistle sound is heard from space in the form of oscillations of the Earth's gravity field. 

Scientists at the University of London have found that due to the size of the sea, it's producing a sound from its seafloor which plays a note of A-flat, although many octaves lower than a piano and not audible to the human ear because it  is nearly 30 octaves below the bottom of a piano' is beyond human hearing range. 

The discovery of this strange noise occurred when researchers at the University of Liverpool were analysing the sea level and pressures in the region over the past 60 years over the period 1958 up to 2013 as well as using information from tide gauges and satellite measurements of gravity using four different models of ocean activity.

Initially looking at ocean pressure in the area, Professor Chris Hughes, an expert in Sea Level Science at the Universityand his team discovered “inexplicable pressure oscillations" across the sea's basin and decided to look closer at what was going on.

Professor Chris Hughes also said-

" We can compare the ocean activity in the Caribbean Sea to that of a whistle. 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.

Similarly, an ocean current flowing through the Caribbean Sea becomes unstable and excites a resonance of a rather strange kind of ocean wave called a 'Rossby wave'. Because the Caribbean Sea is partly open, this causes an exchange of water with the rest of the ocean which allows us to 'hear' the resonance using gravity measurements.                                   "

 Cause for the whistle sound:

'Rossby whistle' which comes from another phenomenon called the 'Rossby Wave'.

Rossby waves, also called 'planetary waves', is a natural phenomenon in the atmosphere and oceans which happens due circulation of waves or currents. A Rossby wave is a wave generated by differences in temperatures of oceanic water levels and by the Earth’s rotation.

'Rossby Whistle' which happens when a Rossby wave- a large wave which propagates slowly to the west in the ocean- interacts with the seafloor. 

This whistle noise is emitted when a large wave dies out on the western boundary of the basin before then reappearing on the eastern side, which the researchers described as a 'Rossby wormhole'.

Only waves of a certain length survive the wormhole, however, and it is these which create the mysterious noise by producing an oscillation over a 120-day period.

With the 'Rossby wave' causing sea levels to vary by as much as 10cm along the Colombian and Venezuelan coasts, scientists also hope that it may help predict the likelihood of coastal flooding.