What causes a hurricane?
It’s a question that has puzzled hurricane chasers and scientists alike for years.
But now Ed Zipser, an atmospheric scientist at the University of Utah, is hoping that research he and a team of scientists are doing this month will unlock the key to this mystery.
The quest to understand the inner workings of tropical storms or depressions and figure out what turns them into full-blown hurricanes is like the quest for the “holy grail” for atmospheric scientists, Zipser said.
But he’s hoping that the experiments he and others are conducting over the next few weeks of hurricane season will provide insights into which physical processes or environmental factors are key triggers in hurricane formation and intensification.
Other factors that the scientists will look at include: whether lightning can be used as a predictor of a storm’s intensity; what role dust from the Sahara plays; and what role does humidity, temperature, precipitation and clouds play?
Tracking the path of hurricanes has been easy in recent years thanks to satellites and supercomputers.
But figuring out which tropical storms or depressions turn into full-blown hurricanes is more guessing game than science.
There are two theories behind the genesis and intensification of a hurricane, Zipser said.
One suggests that the large-scale environment around the storm or tropical depression revs it up and turns it into an intense hurricane.
The other model suggests that small-scale formations or activity about 100 kilometres from the centre are the systems that intensify the hurricane.
“What we don’t know is, if you have strong thunderstorms near the centre of the storm is that making it worse,” said Zipser in an interview with the Star.
“That’s one of the things we’re going to try to find out in this program. We’re trying to understand the relative roles of the large-scale and small-scale environment around and in the hurricane.”
Equally important to the research is the question: Why do some storms simply fail to ignite, and crash and burn into obscurity, never becoming a hurricane.
Zipser, who is one of three scientists helping lead the Genesis and Rapid Intensification Processes (GRIP) experiment, hopes this summer there will finally be a definitive answer to the inner workings of a hurricane.
But much will depend on Mother Nature, he said. “What we hope is that we have two or three storms that intensify and then three storms that look pregnant and fail to intensify.”
The experiment, which is being described as the largest-ever hurricane research project, is using three NASA planes, multiple images from NASA satellites, and four planes from research partners the National Oceanic Atmospheric Agency and the National Science Foundation.
The plan is to use all this flight power to track the storms or hurricanes for 24 hours straight. One of the planes is NASA’s Global Hawk, an unmanned drone plane used by the U.S. Air Force that can fly continuously over a storm system for up to 16 hours. The other planes include a WB-57 and a DC-8.
The team will also be using some state-of-the-art hurricane observation instrumentation – a microwave radiometer and radar will provide insight into the “hot towers” of convection found in cyclones, and a NASA designed and built laser radar will provide measurements of wind speed in three dimensions, including vertically.
“The plan is to take accurate measurements on large-scale and small-scale processes and do it from multiple airplanes several times a day,” explains Zipser.
Zipser and others are hoping the study, which begins Saturday and wraps up on Sept. 25, will provide a more precise view of what is going on below the cloud tops and near the eye of the storm.
-- Debra Black, Staff Reporter