Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Listening for hurricanes

10.04.2008
Acoustic sensors could lead to cheaper early-warning system

Knowing how powerful a hurricane is, before it hits land, can help to save lives or to avoid the enormous costs of an unnecessary evacuation. Some MIT researchers think there may be a better, cheaper way of getting that crucial information.

So far, there's only one surefire way of measuring the strength of a hurricane: Sending airplanes to fly right through the most intense winds and into the eye of the storm, carrying out wind-speed measurements as they go.

That's an expensive approach-the specialized planes used for hurricane monitoring cost about $100 million each, and a single flight costs about $50,000. Monitoring one approaching hurricane can easily require a dozen such flights, and so only storms that are approaching U.S. shores get such monitoring, even though the strongest storms occur in the Pacific basin (where they are known as tropical cyclones).

Nicholas Makris, associate professor of mechanical and ocean engineering and director of MIT's Laboratory for Undersea Remote Sensing, thinks there may be a better way. By placing hydrophones (underwater microphones) deep below the surface in the path of an oncoming hurricane, it's possible to measure wind power as a function of the intensity of the sound. The roiling action of the wind, churning up waves and turning the water into a bubble-filled froth, causes a rushing sound whose volume is a direct indicator of the storm's destructive power.

Makris has been doing theoretical work analyzing this potential method for years, triggered by a conversation he had with MIT professor and hurricane expert Kerry Emanuel. But now he has found the first piece of direct data that confirms his calculations. In a paper accepted for publication in Geophysical Research Letters, Makris and his former graduate student Joshua Wilson show that Hurricane Gert, in 1999, happened to pass nearly over a hydrophone anchored at 800 meters depth above the mid-Atlantic Ridge at about the latitude of Puerto Rico, and the same storm was monitored by airplanes within the next 24 hours.

The case produced exactly the results that had been predicted, providing the first experimental validation of the method, Makris says. "There was almost a perfect relationship between the power of the wind and the power of the wind-generated noise," he says. There was less than 5 percent error-about the same as the errors you get from aircraft measurements.

Satellite monitoring is good at showing the track of a hurricane, Makris says, but not as reliable as aircraft in determining destructive power.

The current warning systems are estimated to save $2.5 billion a year in the United States, and improved systems could save even more, he says. And since many parts of the world that are subject to devastating cyclones cannot afford the cost of hurricane-monitoring aircraft, the potential for saving lives and preventing devastating damage is even greater elsewhere.

"You need to know, do you evacuate or not?" Makris explains. "Both ways, if you get it wrong, there can be big problems."

To that end, Makris has been collaborating with the Mexican Navy's Directorate of Oceanography, Hydrography and Meteorology, using a meteorological station on the island of Socorro, off Mexico's west coast. The island lies in one of the world's most hurricane-prone areas-an average of three cyclones pass over or near the island every year. The team installed a hydrophone in waters close to the island and are waiting for a storm to come by and provide further validation of the technique.

Makris and Wilson estimate that when there's a hurricane on its way toward shore, a line of acoustic sensors could be dropped from a small plane into the ocean ahead of the storm's path, while conditions are still safe, and could then provide detailed information on the storm's strength to aid in planning and decision-making about possible evacuations. The total cost for such a deployment would be a small fraction of the cost of even a single flight into the storm, they figure.

In addition, permanent lines of such sensors could be deployed offshore in storm-prone areas, such as the Sea of Bengal off India and Bangladesh. And such undersea monitors could have additional benefits besides warning of coming storms.

The hydrophones could be a very effective way of monitoring the amount of sea salt entering the atmosphere as a result of the churning of ocean waves. This sea salt, it turns out, has a major impact on global climate because it scatters solar radiation that regulates the formation of clouds. Direct measurements of this process could help climate modelers to make more accurate estimates of its effects.

The research has been supported by the U.S. Navy's Office of Naval Research, ONR Global-Americas, MIT Sea Grant and the Department of Homeland Security Science and Technology Directorate.

Written by David Chandler, MIT News Office

Elizabeth A. Thomson | MIT News Office
Further information:
http://www.mit.edu

More articles from Earth Sciences:

nachricht A promising target in the quest for a 1-million-year-old Antarctic ice core
24.05.2018 | University of Washington

nachricht Tropical Peat Swamps: Restoration of Endangered Carbon Reservoirs
24.05.2018 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>