Predicting Hurricane Intensity: Study
Andrew, Charlie, Frances and Sandy. These are the names of famously destructive hurricanes in the United States that have occurred over the years, and new research may be able to better predict how such storms intensify, leading to improved warning systems.
Thanks to tremendous advancements in computer and satellite technology, scientists over the last 25 years have been able to improve predictions of a storm's intended path. But, there still remains a "cone of uncertainty" of the inner workings of hurricanes.
Hurricane hunter aircraft can help determine wind speed, velocity, water temperature and other data, but this study may have been the first to figure out why or how a storm gets stronger or weaker.
"The air-water interface - whether it had significant waves or significant spray - is a big factor in storm intensity," Alex Soloviev, a professor at Nova Southeastern University's Oceanographic Center, said in a statement. "Hurricanes gain heat energy through the interface and they lose mechanical energy at the interface."
According to NASA, hurricanes - or tropical cyclones - form when warm air from the ocean rises, causing an area of low pressure from below; air from surrounding areas with higher air pressure then push into the low-pressure area. As the warm air continues to rise, the surrounding air swirls in to take its place, growing and gaining speed as the ocean's heat and evaporating surface water feed it.
Soloviev and his colleagues delved further into this process by simulating wind speed and ocean surface conditions found during hurricanes, observing the above-mentioned air-sea interface.
They found that under hurricane force wind, the air-water interface was producing projectiles fragmenting into sub millimeter scale water droplets - a process known as the Kelvin-Helmholtz (KH) instability.
In addition, as wind speed exceeded a Category 1 (74-95 mph), the ocean surface unexpectedly became more "slippery." When the wind exceeded Category 3 (111-130 mph) hurricane force, the "slippery" effect started gradually disappearing and was completely gone at Category 5. The conclusion was that some hurricanes might rapidly intensify to Category 3 and then stay in a "comfortable" zone around Category 3 status.
The researchers concluded from these findings that physical conditions where the air and the ocean interact must be a vital part of any successful hurricane forecasting model and would help explain, and predict, how a storm might intensify as it moves through across the ocean water.
"We've got more work to do, but this is a great first step," Soloviev added.
The results were published in the journal Scientific Reports.