NASA Drones to Spy on Hurricanes, Storm Intensity

By Michael D. Lemonick

Unmanned drone aircraft, which can kill highly targeted enemies without endangering U.S. troops, have become some of the military’s most effective weapons in Iraq and Afghanistan and Pakistan — and also some of the most controversial. As the Atlantic hurricane season moves into high gear, however, two Global Hawk drones will be used for a far more peaceful effort.

As of early September, NASA was geared up to begin sending a pair of drones bristling with meteorological sensors soaring high above oncoming storms to try and get a better handle on the poorly understood question of what makes hurricanes gain or lose intensity as they evolve.

NASA's Global Hawk soars aloft from Edwards Air Force Base, California.
Credit: NASA/Tony Landis

The National Oceanic and Atmospheric Administration (NOAA) has been sending hurricane-hunting planes aloft for years, but they have limitations. “The unique thing about this is that the Global Hawk can fly at 55,000-65,000 feet,” said NASA’s Scott Braun, who’s in charge of the three-year Hurricane and Severe Storm Sentinel (HS3) mission. “It gets us literally above the cloud system. It’s like having a mini-satellite.”

Altitude is key. All sorts of factors might affect a hurricane’s intensity, including ocean temperature, wind speed and direction, humidity, wind shear (that is, wind blowing in different directions at different altitudes) — even the dry air and dust that drifts west from North Africa in what’s known as the Saharan Air Layer.

The drones can measure all of these things for an entire storm, all at once, while the P3 Orion aircraft, flying thousands of feet lower, can only see what’s going on in its immediate neighborhood.

Drones have another advantage, as well. A conventional storm-chasing plane can stay in the air for 10 hours at most, and half of that is wasted in getting out to the hurricane and back. But because the jet-powered Global Hawks are so lightweight, Braun said, they can stay aloft for 30 hours, although they’re limited to 26 to preserve a margin of safety. “They can go all the way to Africa, hang out with a storm, and come back,” he said.

That doesn’t necessarily mean conventional aircraft will become obsolete. The P3 and the Air Force’s WC-130 hurricane hunters have a shorter range and a more limited field of view, but, said Frank Marks, Jr., Director of NOAA’s Atlantic Oceanographic Meteorological Laboratory in an interview, “they’re down closer to the action. Right now the drones and the planes complement each other.”

Flying over the eye of a hurricane.
Credit: NASA.

It may be that the drones will ultimately take over, since, in addition to their other advantages, they pose no danger at all to their pilots, who will be sitting in high-tech trailers at NASA’s Wallops Flight Facility, in Wallops Island, Va.

But the takeover isn’t certain, and figuring it out is one of the HS3 campaign’s primary missions. “The P-3 aircraft are almost 36 years old,” Marks said, “so we have to make some decisions about whether to keep them around. There’s promise here, so we’re partnering with NASA to really take a look at the advantages of flying above vs. flying into the storms.”

This isn’t the first time the Global Hawks have been on hurricane duty, but in previous missions most of their flight time was wasted: the drones operated out of NASA’s Dryden Flight Research Center, in Southern California, and it took them five hours just to reach the Atlantic. From Wallops Island, Braun said, “we can easily get to any storm system in the western Atlantic, the Caribbean, or the Gulf, and have as much as 16 hours on station.”

Each season’s campaign will consist of about 10 flights, and it’s not clear at this point how those flights will be parceled. “I could envision doing five flights over a single storm over a week and a half,” Braun said, “which means you do two storms and you’re done. But those are going to be very well described storms.”

Or maybe, Braun said, the scientists will do more targeted observations at a specific point in the life cycle of, say, five storms. “It depends,” he said, “on how active a season we get where the hurricanes form.”

In any case, the idea for this year is not just to gather data, but also to learn how best to use the aircraft. “When we go out again in 2013, 2014,” Braun said, “we’ll have a much better idea of what we’re doing.”

It will be a few years more before the information they gather can be translated into better intensity forecasts. “We’re really trying to get a handle on the basic science here,” Braun said. “We’ve learned some new things from previous campaigns, but we’ll be collecting some pretty new data, and it will take time to build up a useful amount of information.”

Marks puts it a bit differently. “We’re going to have fun for the next few years.”