Underwater Microphones Can Gauge Hurricane Strength, MIT Says
By Jim Efstathiou Jr.
April 10 (Bloomberg) -- The destructive force of a hurricane approaching land can be measured by underwater acoustic sensors that cost far less than wind-gauging airplanes, researchers at Massachusetts Institute of Technology reported.
Wind speed calculations based on underwater microphones that captured Hurricane Gert's churning in the Atlantic in 1999 were as accurate as measurements taken a day later by an airplane, according to the report, which has been accepted for publication in the journal Geophysical Research Letters.
The microphones are so much cheaper to deploy that storm warning systems can be expanded in countries that can't afford airplanes, said Nicholas Makris, director of MIT's Laboratory for Undersea Remote Sensing and co-author of the report. The current warning system that uses airplanes saves about $2.5 billion a year in potential U.S. storm damage, he said.
``There's a lot of money that's already saved by having accurate warnings, and as you improve it's only going to get better,'' Makris said in an interview. ``The advantages are it's cheap, it's safe and it's relatively easy to do it.''
The best way to measure the strength of a hurricane today is to fly an airplane into the eye of the storm and take wind- speed measurements. Specialized hurricane planes cost about $100 million and a single flight's expenses are about $50,000.
Satellites track killer storms, but can't measure wind speed as accurately as aircraft, Makris said.
`Perfect Relationship'
Underwater sensors promise an alternative. The journal article described how microphones anchored 800 meters from the Atlantic sea floor off Puerto Rico captured sounds of Hurricane Gert that were translated into wind speeds as accurately as aircraft wind-speed readings.
``There was almost a perfect relationship between the power of the wind and the power of the wind-generated noise,'' Makris said.
Hurricane forecasters from Colorado State University yesterday raised the number of Atlantic storms they expect this year to 15, including eight hurricanes. The U.S. East Coast and the Gulf Coast, home to dozens of oil and gas rigs, have about a 45 percent chance of being hit by at least one major hurricane, defined as a storm with winds of more than 111 miles (179 kilometers) per hour. That compares with a historical average of about 30 percent for those two areas, the forecasters said.
Makris will seek to confirm the findings from Hurricane Gert at Socorro, an island off Mexico's west coast that lies in the one of the world's most storm-prone areas. Underwater microphones have been placed in water close to the island, waiting for the next storm, Makris said.
Hydrophones, the underwater microphones, ``provide a way of inexpensively getting an accurate measure of the destructive power,'' Makris said. Countries that lack money for aircraft monitoring ``could really benefit from that.''
To contact the reporter on this story: Jim Efstathiou Jr. in New York at jefstathiou@bloomberg.net.
Last Updated: April 10, 2008 16:38 EDT
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