TBO.com - TBO is Tampa Bay Online

Scientists Go Deeper To Find Clues To Hurricane Intensity

ADVERTISEMENT

By ANNA SCOTT

Sarasota Herald-Tribune

Published: August 30, 2008

GULF OF MEXICO - For nearly seven hours, at intervals of about six minutes, flight engineers pop open the floor hatch.

Through the narrow tunnel is a small, oval view of waves.

And 3, 2, 1, drop!

Twelve pounds of radar shoots from the belly of the plane and plunges 8,000 feet to the Gulf of Mexico. A parachute slows its fall. Saltwater activates the battery pack and a lead weight pulls the temperature gauge to the bottom. Air fills a flotation device to hold the radio wave transmitter steady on the surface.

From the hurricane hunter aircraft named after Miss Piggy of "The Muppet Show," scientists record the temperature as the sensor drifts below the surface.

The radar buoys, called Airborne Expendable Bathythermographs, travel 1,200 feet, about one-tenth of the way to the ocean floor, in less than 10 seconds.

If the water is warm at that depth, and in this case about 62 degrees Fahrenheit is considered warm, the scientists take note. Should Hurricane Gustav pass over one of these spots, it could swell in a matter of hours, the theory goes.

The plane, a WP-3D four-engine turboprop, carves a 2,000-mile zigzag across the Gulf, leaving a trail of clues to one of the most pressing mysteries in hurricane forecasting.

The study of how deep, warm-water currents in the Gulf and Caribbean Sea can build hurricane intensity is relatively new. Nick Shay is directing most of the research.

"It's been a culture change," said Shay, who works with the federal government's hurricane research division and conducted Thursday's data-collection mission over the Gulf. "Before this, all anyone talked about was sea surface temperature. We had to convince them it was about the water temperatures down deep. We have a lot more to do, but at least it's part of the vocabulary now."

In 1988, scientists rigged radar buoys in the Gulf after Hurricane Gilbert made landfall at Cozumel, Mexico, as a Category 5 storm. They discovered an area of deep warm water that appeared to have been located in its path when it intensified. They did not think much of it.

By 1995, when a map of ocean heat showed that Hurricane Opal intensified when it passed over a similar deep pool, scientists began to pay closer attention. In the following years a similar pattern was found with other major storms that intensified rapidly. Hurricanes Isidore and Lili. Hurricanes Ivan and Charley. Hurricanes Katrina and Rita.

Hurricane forecasters were persuaded enough to add deep ocean heat content to their intensity forecasting model. Shay estimates an increase of about 4 percent in the accuracy of hurricane intensity forecasting since then, and about 6 percent in accuracy for major storms.

Federal researchers are directing more money and attention to intensity forecasting, having established more reliable storm tracking methods in the past decade.

But the field is mostly wide open, with calls for all kinds of studies and new technology, including better satellite images that show finer, more detailed views of hurricanes. Historically the emphasis in hurricane forecasting has been more on the atmosphere.

On Thursday his research team was armed with surplus radar buoys from the Navy that are about 30 years old. Some of the packs did not record any information, nor were they sophisticated enough to detect salt levels or current motion, key factors in predicting heat levels.

The best radar packs would cost $1,500 each. Shay's best hope for those at this point is a federal grant as part of a project to predict hurricane impacts on oil rigs in the Gulf.

Share this:

Loading Comments...

Email Print

ADVERTISEMENT