A high-flying, long-endurance drone that once spied for the U.S. Air Force is in the final phases of a tryout for the National Oceanic and Atmospheric Administration as a storm chaser. So far, the judges are impressed. The aircraft – the Global Hawk, and one of the first ones built – has successfully flown observational patterns directly above five Atlantic hurricanes over the past two years, dropping data-gathering canisters called sondes and taking atmospheric readings with sensors.
The information it has provided has helped to guide emergency forecasts from the National Weather Service in Miami. Over the next six months, NOAA leaders will further examine what the Global Hawk has contributed and what that has cost, as it assesses continuing to use it that way. “We’ve just had our most successful season … because we had the right number of storms that we wanted to sample,” says Robbie Hood, director of NOAA’s Unmanned Aircraft Systems program, which is leading the trial in collaboration with NASA. The trial is part of a project called SHOUT, which stands for Sensing Hazards with Operational Unmanned Technology. A particular highlight, Hood notes, came when data gathered by the Global Hawk was used to upgrade Hurricane Gaston from a tropical storm in August. “Impact analysis is still ongoing,” Hood says. “But we do feel like we are seeing enough positive results that the Global Hawk could add value, whether as a forecast tool in addition to our satellites or as an augmentation.”
SHOUT started with roughly $9 million from the Disaster Relief Appropriations Act of 2013. Commonly known as the Sandy Supplemental, the legislation was spurred by Hurricane Sandy, the worst hurricane the United States had faced since Katrina in 2005. Sandy pummeled the East Coast in October 2012 and killed at least 145 people in the United States, Canada, and the Caribbean. “After Hurricane Sandy, many people realized how important the weather forecasts were to making sure that everybody was prepared,” Hood says. A particular concern was that there might be a gap in coverage by weather satellites as older satellites were replaced. “There are several projects that have been working on that issue,” Hood says. “Some are looking at how you might extend the life of older satellites. Others are looking at other kinds of observations. We were chosen to look at using high-altitude UAS observations.”
Enter the Global Hawk, a retired spy drone that NASA had already adopted from the Air Force. It flies as high as 63,000 feet. That’s about 20,000 feet higher than manned Hurricane Hunter aircraft — high enough to stay above storms, but low enough to get a good look at them. A good, long look. The Global Hawk can stay in the air up to 26 hours, two to three times longer than most manned aircraft. Instead of using the drone just for studies and experiments, SHOUT set up an extended tryout for the Global Hawk as an operational addition to the current mix of platforms that gather weather data for immediate use in hurricane forecasts. “What we want to do is show how you could use a Global Hawk in an operational format on a regular basis,” Hood says. “So if you lost your satellite, or if you wanted to augment the satellite, could you fly the Global Hawk every single summer during hurricane season and add value to the data that’s already being collected?” It makes sense to use a combination of data-gathering platforms for storm forecasts, because each has comparative strengths and weaknesses, members of the SHOUT team explained.
- Satellites provide global coverage like nothing else. But images from orbit are fairly coarse, compared with what the Global Hawk can provide. “It’s like maybe going from an X-ray to an MRI,” says Gary Wick, lead science officer.
- Satellite readings cover the globe on a set schedule, whereas the Global Hawk can be dispatched more spontaneously to focus on a smaller area continuously. “You can think of it almost as a roving satellite,” says SHOUT project manager Philip Kenul.
- The Global Hawk is more fuel efficient than manned aircraft. With a wingspan of 116 feet and a weight of about 22,000 pounds, it is a large drone, but it operates with only one engine that burns about 75 gallons of fuel per hour. The WP-3D, a manned Hurricane Hunter aircraft, has a wingspan of about 99 feet, weighs about 135,000 pounds fully loaded, has four engines, and burns about 750 gallons of fuel per hour.
- So far, only manned Hurricane Hunter aircraft can actually be flown into the eye of a hurricane. The Global Hawk generally stays above storms. “Where we are out there flying, most of the time it’s just really smooth air,” says Global Hawk pilot Jon Neuhaus.
The SHOUT team will present its findings on the Global Hawk’s hurricane work in June, Hood says. But even if the ruling is to stop using the drone as a storm chaser, enthusiastic trials of unmanned systems for weather observations will continue. Hood notes that SHOUT’s work with the Global Hawk has attracted inquiries from potential partners in other countries that are interested in using the drone with different sensors to better monitor changes in Arctic sea ice. In addition, a private company has approached NOAA about partnering on the development of a solar-powered high-altitude drone that could fly for months at a time. “It is such an exciting time for unmanned aircraft systems,” Hood says. “And this has really spurred us forward.”