Building a Better Hurricane Forecast
Hazel, Donna, Fran, Floyd, Isabel. North Carolina has been smacked so many times by hurricanes that coastal residents are on a first-name basis with some of the worst storms. According to the State Climate Office, a hurricane makes landfall in North Carolina once every four years, and three-fourths of those that have come ashore since 1950 have been major hurricanes. Some people fear that global climate changes will produce even stronger storms in the future, so NC State researchers are trying to gain a better understanding of hurricanes and devise more accurate forecasts.
Using the supercomputer horsepower of the Renaissance Computing Institute, a collaborative program with NC State, UNC-Chapel Hill and Duke University, Dr. Gary Lackmann, a professor in the Department of Marine, Earth and Atmospheric Sciences (MEAS), and his research team simulate both real and hypothetical hurricanes to gauge the impact of climate change on tropical systems. Some simulated hurricanes are allowed to reach their maximum intensity so researchers can see how they peak in current conditions and those forecasted for the late 21st century by the Intergovernmental Panel on Climate Change (IPCC). "Much of climate change depends on what people do in the coming years," Lackmann says. "So, we must consider a range of solutions."
Lackmann's team uses data from past hurricanes and IPCC projections for sea-surface temperatures, water levels, humidity, and other variables to see what a hurricane like Fran or Floyd might look like in 50 to 75 years. The simulations helped them determine that current storms forming in more humid environments grow larger, with more extensive spiral rain bands at their outer edges. "The strongest storms in the future will likely be slightly stronger than those today, and they will produce heavier rainfall," Lackmann says. "Ocean temperatures will rise, but so will atmospheric temperatures, which will mitigate the increased strength of tropical systems."
MEAS professor Dr. Lian Xie, who has become known for the accuracy of his annual forecast of Atlantic hurricane activity, is developing a computer program to forecast further into the future to discern any impact from climate change. Xie uses a statistical model for the seasonal forecasts, but it cannot predict beyond one year nor foresee record-breaking events because it generates a probability of what will happen in current conditions based on activities in previous years. His new model differs from those Lackmann uses because his seasonal forecasts cover a larger area over a longer time frame. "The dynamic model we're developing will enable us to forecast hurricane activity in both today's environment and in the climate of the future," Xie says.
Agencies providing funding for research cited in this story include: