AtmoSci alum works to improve hurricane forecasts

When meteorologists along the coast start predicting hurricanes later this year, they’ll be relying on data from a UWM alum working almost 2,000 miles away.

Christopher Rozoff is a project scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. He and a team of scientists are studying some of the deadliest natural disasters to strike the United States. Their question: How you can tell which hurricanes will be mild and which ones will become the next Katrina?

“I’m specifically interested in improving the prediction of hurricane intensity, which has proven to be a difficult problem,” Rozoff said.

An eye on the weather

Rozoff has been a weather geek since he was a kid. That love of storm-watching and identifying clouds carried into his college career when he entered UWM and majored in atmospheric sciences and mathematics. He remembers being surprised by just how exciting and informative his classes were.

“The atmospheric science program had really top-notch professors and the classes really prepared me well,” he said. “When I got to graduate school at Colorado State University, I felt ahead of the curve.”

After graduate school, he took a postdoc position at UW-Madison where he collaborated with scientists across the country for research projects that eventually helped him land a position with NCAR.

Atmospheric Science alum Chritophers Rozoff (right) prepares to fly into the center of Category 3 Hurricane Irene in 2011. The flight reached 10,000 feet above a turbulent sea. Flying with Rozoff is Matthew Sitkowski, an executive weather producer now at the Weather Channel. Photo courtesy of Christopher Rozoff.

The National Center for Atmospheric Research is a multidisciplinary lab that has a finger in almost every weather-related pie. From climate to solar dynamics to theoretical meteorology, scientists at NCAR collaborate with universities and researchers around the world on topics that will help society better understand our atmosphere.

“It’s just a very exciting place,” Rozoff said. “The best aspect of my job is being able to go to work and learn something new every day. Some days are headaches where you just run into debugging computer codes and other dead ends, but even that’s rewarding because turning roadblocks into puzzles to solve often leads to new successes and rewards.”

Lately, Rozoff spends his time using machine learning to improve upon operational numerical weather predictions of hurricane intensity. He and his colleagues examine old forecasts and compare them to what actually happened during a given hurricane event. Then they feed that data into machine learning algorithms to produce forecasts that have less errors than the baseline operational models.

“We can use that information with machine learning techniques to improve hurricane threat predictions,” Rozoff said. “With those techniques, we can better predict hurricane tracks and where they may make landfall, to understand the size of a storm, and to estimate other aspects, such as rainfall.”

An eye on the storm

There several factors that contribute to the birth of a hurricane and how intense it will be. Hurricanes are driven by both large- and

small-scale weather patterns that are seemingly random and often imperfectly observed. Those include individual thunderstorms within the hurricane core, the ocean, and the turbulence in the lower levels of the atmosphere.

Some studies have suggested that climate change and rising global temperatures will lead to an increase in the number of severe hurricanes, but Rozoff said even that information is uncertain.

“There are a lot of negative factors that get increased too, with climate change,” he said. “For example, the Atlantic Ocean may experience higher vertical wind shear, which is a measure of the change of wind with height, an adverse factor for hurricane intensity. A warmer ocean, of course, provides more fuel for the storm. But then again, in the Pacific Ocean, there’s some evidence that with climate change, the upper part of the atmosphere will become warmer as well. That could mean more atmospheric stability, which decreases hurricane intensity.”

One thing is certain: A warmer atmosphere is capable of holding more water vapor, so while hurricanes may not increase in intensity or frequency by huge numbers due to climate change, areas hit by these storms will almost certainly receive more rainfall than they did in the past, leading to flooding.

Each hurricane season is another chance to test his work. Rozoff hopes the data he generates will be able to help forecasters better predict hurricanes and their intensity so that they can keep communities safe.

“That’s the overall hope for sure,” he added. “To be able to apply the tools that we’ve developed to improve the prediction is really fulfilling.”

By Sarah Vickery, College of Letters & Science