'Cheaper way' to predict hurricanes
Listening to hurricanes from the ocean depths could provide a cheap and effective way to predict their destructive power, scientists believe.
Currently the strength of a hurricane can only be measured by sending specialised aircraft into the eye of the storm.
Each of these planes costs around £50 million, and a single flight costs about £25,000. Monitoring an approaching hurricane might require a dozen flights.
An easier and better way to gauge the power of a hurricane, or tropical cyclone, could be to listen to the noise it makes as it passes over the ocean, new research suggests.
Wind strength could then be calculated from the intensity of the sound, caused by the storm churning up the water in its path.
Evidence that the idea works emerged when scientists discovered a hurricane which had been recorded by a hydrophone, an underwater microphone, in 1999.
Hurricane Gert happened to pass almost directly over the hydrophone anchored at a depth of 800 metres in the middle of the Atlantic.
During the Cold War, microphones of this type were planted in the Atlantic by the US military to listen out for Soviet submarines. Today, many have been employed for research, often to record the sounds of earthquakes.
The sound picked up by the hydrophone measured the power of the hurricane just as accurately as the aircraft used to monitor the same storm 24 hours later.
Dr Nicholas Makris, director of the Massachusetts Institute of Technology's Laboratory for Undersea Remote Sensing, said: "There was almost a perfect relationship between the power of the wind and the power of the wind-generated noise. There was less than 5% error, about the same as the errors you get from aircraft measurements."
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