Drone, Sensors May Open Path Into Eye of Storm

By Christopher Lee
Washington Post Staff Writer
Monday, October 8, 2007

The 2007 hurricane season has been relatively quiet, but whenever the next big cyclone spirals into life in the open ocean and takes aim at the U.S. coast, Joseph Cione will be ready to plunge into it.

Not literally, of course. Cione, a hurricane researcher with the National Oceanic and Atmospheric Administration, is the lead scientist on a government project that aims to send an unmanned aerial drone with advanced weather-watching equipment deep into a hurricane for the first time, and at the earliest opportunity.

The goal is to fly the 28-pound craft as low as 500 feet, gathering detailed observations of the high-wind, low-altitude eye-wall regions that are too dangerous for manned hurricane hunter airplanes to probe. By learning more about the lowest layers of the storm, scientists hope to better understand the energy transfer from the ocean to the atmosphere that fuels hurricanes and causes them to intensify and grow more deadly.

"This gives us a better understanding of that region," Cione said. "Over the last 30 years, we've made significant improvement over time with [predicting] track, meaning where the storm is going to go. We have not made that improvement hardly at all with intensity change. There are many reasons why. One of the reasons is that this region, down very low, is very important. It's where the energy transfer occurs."

The drone, known as an Aerosonde after the Australian company that designed it, is one of several emerging technologies being used to help unlock the secrets of hurricanes and, scientists hope, give rise to more accurate computer models. Better and earlier forecasts, particularly of a storm's intensity, can help drive decisions to evacuate regions and save lives.

Another novel tool is the North American Lightning Detection Network, a growing network of more than 180 highly sensitive land-based remote sensors that can study storms from hundreds or even thousands of miles away. In a study to be published early next year in the Monthly Weather Review, a journal of the American Meteorological Society, scientists will report that it may be possible to gauge when and whether a hurricane will intensify by using the sensors to examine the frequency of lightning strikes within the eye wall.

And earlier this year NOAA significantly upgraded its weather and climate supercomputers so that its systems, which can process more than 240 million global observations every day, are now among the world's fastest. With them, meteorologists are able to generate more advanced models of storm behavior that they hope will make predicting hurricane intensity easier.

The most captivating of the new technologies may be the drone. With a wingspan of nearly 10 feet, the propeller-driven orange and white aircraft can be launched from the roof of a sport-utility vehicle and can fly 1,200 to 1,300 miles round-trip. Scientists initially steer it by radio control using a joystick, then, at greater distances, via satellite.

Its instruments record moisture, temperature and pressure, as well as ocean surface temperatures and, of course, wind speeds. The data is sent to scientists at the National Hurricane Center in Miami via satellite and made available to forecasters immediately.

Traditionally, hurricane hunter aircraft have dropped bundles of instruments through storms, which provide only a momentary look at a limited cross section. But the Aerosonde collects data continuously, yielding a fuller picture of where and how powerful the strongest winds are and helping to predict what the storm surge will be.

Two years ago, researchers sent a drone on a 10-hour mission into Tropical Storm Ophelia, but they are eager to probe a hurricane, the most powerful of which have sustained winds of more than 155 mph. Cione has stationed "rapid response" teams to launch drones at a NASA facility in Wallops Island, Va., and at Key West Naval Air Station in Florida until Oct. 31 in the hopes of catching a hurricane within range.

The earlier flight showed the fragile-looking drone to be remarkably rugged, said Cione, who is not worried about it being torn apart.

"It's better to be small," he said. "The scales of turbulence are pretty large relative to the craft, so they kind of sneak between these big eddies, if you will. They also right themselves very quickly. These things are pretty robust. They'll get tossed around a little bit, but then they'll right themselves."

Its size also makes the drone quite economical on fuel. Cione compared the 24-cc. fuel-injected motor to that of "a fancy lawnmower," and noted that in the 10-hour Ophelia flight the craft burned less than two gallons of gasoline.

Other forecasters are working to learn more about hurricanes with land-based instruments.

Kirt Squires, a meteorologist with the National Weather Service, co-wrote the new study of the relationship between lightning frequency near the eye of a hurricane and a storm's intensity. Squires and a colleague at the University of Hawaii, where Squires recently completed his master's degree, analyzed data on intensity and lightning strike rates from hurricanes Katrina and Rita, the disastrous storms of 2005.

They combined data from the remote sensor network with readings from NOAA's hurricane hunter aircraft and a NASA weather satellite. The ground-based sensors, about the height of a person and topped by a white bulb, can detect electromagnetic signals produced by cloud-to-ground lightning strikes from thousands of miles away.

Researchers found that outbreaks of greater lightning activity were associated with periods when Katrina and Rita were gathering strength. They think that the conditions that fuel a hurricane's intensity -- the energy transfer that occurs when water condenses from vapor into droplets, releasing heat and causing updrafts of air -- also give rise to more lightning strikes in the heart of the storm.

"It's not that the lightning itself is intensifying the storm," Squires said. "It's the fact that if the updrafts and the eye walls are getting stronger and the hurricane is getting stronger, then we should see an increase in the amount of lightning. . . . Both storms contained their highest lightning outbreaks during their rapid intensification period."

Forecasters are not using lightning data in their intensity predictions yet, but Squires says that they might if further study bears out the relationship.

"No matter how good this ever gets, no one would ever just solely go on lightning strikes to forecast a hurricane," he said. "But it's another tool."

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