When a hurricane forms out at sea, two NOAA and one navy aircraft equipped with Doppler radar will fly into and around the storm, taking measurements of the atmospheric structures that comprise the hurricane. In addition to designing the aircraft flight patterns for optimal sampling, UM’s RAINEX scientists and collaborators will launch “dropsondes”—instruments that measure temperature, humidity, and atmospheric pressure—into the storm.

“The goal of the research is to understand the interactions of the wind fields—the circulation within the hurricane, the outer rainbands, and the large-scale environment around the hurricane—to see how these structures change with time to increase or decrease the intensity of hurricanes,” says Shuyi Chen, associate professor of meteorology and physical oceanography and a lead investigator on the $3 million NSF-funded project. “After the flights, we’ll analyze the Doppler data, which will tell us the rainfall and the wind speed and direction in three dimensions through the length and width of the hurricane.”

RAINEX is one of numerous projects scientists at the Rosenstiel School are conducting to better understand how hurricanes behave, to improve hurricane forecasts, and to mitigate the effects these storms have on natural ecosystems and society.

“There’s a pretty broad-brush approach to hurricane-related research at the University,” says Otis Brown, dean of the Rosenstiel School. “We have a range of people, from those who fly into hurricanes and observe tropical cyclone dynamics to those interested in forecasting surge and wave fields. Others are interested in the ‘Well, what happened?’ part, whether it’s the hurricane’s effects on marine or shoreline ecology or the economic impacts on society.”

Sharan Majumdar, assistant professor of meteorology and physical oceanography, has developed a computer technique that will eventually help NOAA direct its reconnaissance planes to the areas most likely to yield useful hurricane data. NOAA began applying his strategy on a limited basis during the 2004 hurricane season to collect information on Hurricanes Charley, Frances, Ivan, and Jeanne.

“NOAA planes now sample from all around the storm, but we want to be more selective about where to fly,” Majumdar says. “For example, it may be calm to the south of the hurricane. But to the north there may be a high- pressure system that steers the storm toward the east coast. We’ll take measurements to determine if the high pressure system is going to continue to strengthen and whether that will influence the direction of the storm.”

In 1995, as Hurricane Opal came barreling up Florida’s coast toward Pensacola Beach, the storm escalated in two days from a category 1 to a category 4, packing winds of 145 miles per hour. Fortunately, Opal weakened just before hitting land. David Nolan, assistant professor of meteorology and physical oceanography, wants to find out why hurricanes such as Opal intensify so quickly. He is doing both computer modeling and fundamental research in physics and fluid dynamics to determine what makes the vortex (center) of the storm stronger or weaker.

“When a tropical storm begins developing, it’s very disorganized. But as the wind field becomes more structured, it uses energy released in the clouds and thunderstorms more efficiently,” says Nolan, who also is looking at whether larger or smaller hurricanes intensify more rapidly, given the same environmental conditions.

At the Rosenstiel School, faculty view themselves as basic researchers seeking fundamental knowledge about hurricane behavior. Ultimately, though, they lay the groundwork for what are termed “operational systems,” the computer models used by NOAA and the National Hurricane Center to forecast a hurricane’s track and intensity. Before being integrated into an operational system, the research must go through a long testing process via NOAA’s Joint Hurricane Testbed Program, explains Lynn (Nick) Shay, professor of meteorology and physical oceanography. Four years ago, the National Hurricane Center integrated Shay’s work on upper-ocean heat content into its Statistical Hurricane Intensity Prediction Scheme (SHIPS). In 2004 his methods for describing how energy is transferred between the ocean and atmosphere helped reduce forecast errors on Hurricane Ivan by 15 percent.

In his laboratory, Shay uses data from aircraft, weather buoys, and satellites to measure subtle changes in the height of the ocean’s surface. These changes reflect areas of warmer or cooler water. He then produces daily heat-content maps that are integrated into the SHIPS systems at the operational centers.

“Our NSF-sponsored research shows that when atmospheric conditions are favorable, warm pools can significantly strengthen a storm,” he says. “Last summer, Hurricane Ivan remained a dangerous category 4 and 5 hurricane as it went over a deep pool of warm water in the northwest Caribbean Sea. But when it went over the Gulf of Mexico, it went down to a category 3 because the warm layers of the gulf were relatively thin compared with those of the Caribbean.”

ne of the most perplexing problems faced by hurricane forecasters is determining which communities will be affected by coastal flooding and dangerously high winds and waves. Hans Graber, professor of applied marine physics, and his colleagues have developed a coupled real-time forecasting system that provides information about hurricane winds at ground level, where they do the most damage. Using data from hurricane hunter planes, satellites, and weather buoys, the system creates high-resolution, ground-level “snapshots” of hurricane winds close to the ocean. Graber then uses these snapshots to create five-day probability forecasts outlining potential damage on coastal strike zones. If consistent with its other models, the National Hurricane Center will transition Graber’s maps into its mainstream operations.

In addition to his work with storm surge and wave predictions, Graber codirects the Center for Southeastern Tropical Advanced Remote Sensing (CSTARS). This advanced satellite facility downlinks satellite and radar images of hurricanes over the ocean and converts this information into high-resolution maps showing hurricane winds at the surface of the ocean for use by the National Hurricane Center.

“This is critical because radar can provide images of the hurricane at the ocean’s surface all day and night and through clouds,” Graber says. “The optical sensors now being used provide only daytime information, and that information is limited to clouds at the top of the hurricane.”

Most of the time, Rosenstiel School students and faculty are ensconced in offices, analyzing previous hurricane data. But during hurricane season, folks divide into two camps.

“Most people go home to prepare,” Dean Brown says. “But Shuyi, Sharan, Nick, and Dave are like kids with a new toy. They’re eager to see what the hurricane is going to do. At the end of the day, the people at the Rosenstiel School are paid to be intensely curious. And that’s what makes this a really good job.”