Wednesday, May 21, 2008

Hearing Hurricanes

Hearing Hurricanes

David Chandler, MIT News Office

April 9, 2008

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. Click here to listen to an enhanced, but very low-frequency, audio version of the underwater sound of 1999’s Hurricane Gert (above, in a colorized infrared image, courtesy of NOAA).

Hurrican Gert

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 800 meters deep 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.

Acoustic sensor
An acoustic sensor key to the joint MIT-Mexico hurricane research is deployed off the coast of Isla Socorro by crew members of the Mexican Research Vessel Altair.

The case produced exactly the results that had been predicted, providing the first experimental validation of the method, Makris said. “There was almost a perfect relationship between the power of the wind and the power of the wind-generated noise,” he said. 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 said, 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 said. 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 explained. “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 is 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.

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Emergency planners talk about tornadoe

Wednesday, May 14, 2008 5:51 PM CDT

County finalizes disaster preparation plan

By Warren Watkins
The Daily Citizen

With tornadoes skipping and hitting around White County, killing dozens and doing millions of dollars in damage across the state this year, interest in weather safety is keen among local citizens.

Tornado siren sounds were explained by Tamara Jenkins, chairman of the Local Emergency Planning Committee, at the regular monthly meeting Tuesday.

“We have a warning tone, which is a constant horn that may go up and down in tone slowly as the siren rotates,” Jenkins said. “It is repeated every three to five minutes automatically until the ‘all clear’ is sounded manually. The ‘all clear’ tone goes up and down quickly from high to low.”

At noon every Wednesday the tornado sirens are tested all over the county, including Searcy.

“Tornado sirens in the county are set off by the county 911 dispatch center,” Jenkins said. “We can do individual towns. We don’t have to set off the whole county.”

Some Jackson County sirens which can be heard in Velvet Ridge are different in tone, Jenkins said.

“As long as we have a tornado warning in effect for the county, the sirens will go off periodically,” said Conway Helm, a Higginson firefighter.

Used to warn people who are outside, not inside a building, tornado sirens are complemented by radios, sold in local retail outlets, that warn those inside buildings of bad weather.

“We’re pushing all-hazard radios now,” Jenkins said. “You’ll also get notified of hazardous spill evacuations with them.”

In other business, Jenkins told the committee the county’s mitigation plan had been updated since Hurricanes Katrina and Rita hit and would soon be uploaded to the Internet. The mitigation plan, a proactive blueprint for planning ahead to minimize damage from natural disasters such as floods, tornados and earthquakes, has been approved by the Federal Emergency Management Agency (FEMA).

“In the mitigation plan we identify the possibilities and try to prepare for what the county can do to help people in areas before a disaster hits — maybe we can raise roads or something,” Jenkins said.

The county’s emergency operations plan was completed earlier and is found online at the White County Sheriff’s Office Web page, That plan details how resources in the county will be used in the event of a disaster.

“Had the City of Clinton known we had a mobile command unit, they would have requested it during the aftermath of their tornado because they lost all power in their police station,” Jenkins said.

The gymnasium at Arkansas State University-Beebe has now been designated as a mass feeding station and restroom facility in the event of a disaster.

As of May 7, there were 46 individuals who have applied for assistance from FEMA for damage resulting from flooding along the White and Little Red rivers in White County and $78,000 has already been disbursed.

The county with the most applications from that flooding so far has been Phillips County, with 249, and Woodruff County leads with largest amount disbursed with $235,000.


More than 700 escape blazing ferry

More than 700 passengers escaped from an Indonesian ferry that caught fire shortly before reaching its destination on Borneo, officials said.

The ship was making its way upriver to the port town of Sampit when flames broke out on the top passenger deck, assistant police Lt Suwarno said.

All passengers were believed to have been safely evacuated, said district chief Wahyudi Anwa. Four people were taken to hospital, he said.

The boat was approaching Sampit in the Mentaya river, around 500 miles north-east of Jakarta, when the fire started, said Mr Suwarno, who like many Indonesians goes by a single name.

The ferry had travelled from Surabaya, the provincial capital of East Java, to Central Kalimantan on the Indonesian half of Borneo, with at least 706 passengers and 22 crew.

Boats are a main source of transportation in Indonesia, a vast archipelago with more than 17,000 islands. Overcrowding and poorly enforced safety standards cause frequent accidents.