An Aquatic Drone Is New England’s First Line of Hurricane Defense

The submersible glider, launched by UMass Dartmouth, collects and shares data related to oceanic storm activity in the area between Martha’s Vineyard and New Jersey.

by Jennette Barnes, The Standard-Times / October 29, 2018

(TNS) — The next time a hurricane comes barreling toward New England, we may have a better idea of whether it will intensify to a Category 5, or fizzle out and bring less damage than everyone feared.

Just thank the underwater hurricane patrol.

This hurricane season, an unmanned submersible named Blue is keeping watch over an area between Martha's Vineyard and New Jersey, collecting data shared around the globe.

Named in honor of blue whales, the torpedo-shaped glider operated by UMass Dartmouth is part of a string of gliders deployed by the U.S. government, universities and others on the East Coast and in the Gulf of Mexico and Caribbean.

The gliders record ocean conditions that can be used to sharpen the forecast not of where a hurricane will go — the so-called "cone of uncertainty" — but of how bad it will be.

That could mean the difference between evacuating and staying put.

"Knowing the ocean is important," said Wendell Brown, a professor at UMD's School for Marine Science and Technology and the principal investigator on the SMAST glider research.

Researchers working on the glider project say predictions of the path of a hurricane have improved tremendously, but its severity not so much.

"The errors have remained very large," said Gustavo Goni, a meteorologist and researcher for the National Oceanic and Atmospheric Administration.

He said scientists linked heat in the water to the intensification of hurricanes 15 or 20 years ago, and the glider research takes the next step.

"Now what we're trying to assess is how much of a role the ocean plays," said Goni, who works for NOAA's research arm in Miami.

The SMAST team launched Blue on Aug. 6. Starting at 7 a.m., Brown and his team of graduate students and an intern loaded their equipment onto the Lucky Lady, a 50-foot former fishing boat operated by SMAST, and docked at the Fairhaven Shipyard.

They motored out two hours to a point west of Martha's Vineyard, plunked Blue into the water, conducted some preliminary tests, and sent it on its way. The five-foot yellow glider looks almost like a torpedo, but it has wings that allow it to glide up and down as it changes buoyancy.

New This Year

Although this is Blue's 10th mission, the 2018 hurricane season is the first time gliders from Massachusetts to Puerto Rico have been fully coordinated, sending their data to a central tracking system. Researchers analyze the data and provide it to their counterparts around the world.

"Everyone agrees that collaborating to improve hurricane forecasts is a good thing for everybody," said Scott Glenn, a distinguished professor in the Department of Marine and Coastal Sciences at Rutgers University.

SMAST's work with Blue is part of a NOAA-funded research grant led by Rutgers.

Scientists call these chains of gliders "picket lines" — as in sentinels standing guard.

"It's like a soccer game," Glenn said. "Some people chase the ball, and some people protect the goal. The gliders protect the goal."

Cold water can dampen the power of a storm. Ocean temperature, salinity and density affect whether a hurricane is likely to churn up cold water from below the warm layer at the surface.

Most glider data are transmitted in real time, even when hurricane-force winds are churning the ocean. They get assimilated into a model that includes satellite observations and readings from other instruments. Then, meteorologists couple the ocean model with an atmospheric model to create a forecast.

When hurricanes make landfall where waters are warm year round, like this month's Hurricane Michael in the Gulf of Mexico, "the only thing they see is fuel," Goni said.

Last year, gliders recorded data from Hurricanes Harvey, Irma, Maria and Jose.

What's exciting about that, Goni said, is the impact of glider data on those storms was bigger than any other instrumentation in the ocean, and sometimes bigger than all the other ocean instruments combined.

Still, he doesn't want to pull anyone else's research down.

"The most important thing is to represent the ocean correctly," he said.

How It Works

Blue moves autonomously. To dive, it draws water in, making itself heavier than the surrounding water. To surface, it releases the water, which makes the glider more buoyant. It surfaces about every three hours, alerts the research team, and beams data to the command center at Rutgers in New Brunswick, New Jersey.

The information is distributed internationally.

"So we act locally, but our information is available globally," Brown said.

He said the glider moves in a "sawtooth" pattern, up and down at half a mile per hour, taking measurements at different depths. If it didn't have wings, it would just sink when it draws water, but the wings allow it to glide toward the sea floor. When it detects the sea floor acoustically, it pushes water out and heads toward the surface.

It travels about 100 miles out, "to what I call the edge of the ocean," Brown said — that is, the end of the continental shelf, where the water is more than 300 feet deep. It passes the shelf break and goes out over the continental slope, then hangs a right toward New Jersey. Later it takes another right and returns to the deployment site, drawing a rough a triangle that can be seen on a tracking map online.

The work is part of the Mid-Atlantic Regional Association Coast Ocean Observing System, known as MARACOOS, which is a member of NOAA's Integrated Ocean Observing System.

Brown said NOAA funded this year's mission because measurements Rutgers made in 2011 in the path of Hurricane Irene showed how the action of the hurricane and the ocean conditions brought cold water to the surface and dampened the hurricane's intensity. That made the surface water colder than storm models assumed.

"By the time it reached New York City, its intensity was less than forecast, and that convinced the powers [that] be that having gliders in the water was an important part of the national effort to forecast hurricanes," he said.

Although Irene made landfall in multiple locations and caused massive damage, including unprecedented river flooding in Vermont, the flooding in New York City was nowhere near what people feared.

"It took Sandy, a different kind of storm, to flood New York City," Brown said.

David Epstein, a meteorologist at WBUR Radio and The Boston Globe who is not affiliated with the glider project, said Irene was worse than predicted for northern New England.

Hurricane forecasting falls into two big buckets: water and air, and both have gotten better over the years, he said. Understanding how they work together, "that's the challenge."

According to Epstein, average annual hurricane strength has not changed much. But scientists are studying how unusual weather patterns happen. If 40 inches of snow a year is normal, but it all comes in February, "that's a hell of a February," he said.

The more data the better, but there will still be surprises, he said.

What's Next

NOAA's research unit hopes that next year, it can add more gliders to the coordinated effort and build a complete network. Goni said he believes it can happen because of strong support from NOAA, which is important, because the project needs personnel, resources and equipment.

Brown expects NOAA will ask SMAST to send a glider out on more season-long missions. This is Blue's first time spending so long at sea. His team switched the battery power to lithium to allow Blue to stay out for 80 to 90 days, compared to the 30 days it stayed out when SMAST first received the NOAA-funded glider in 2011.

Blue is still at sea. Brown plans to pick it up later this fall, in the same location where it was deployed.

Blue may need to be replaced soon, especially with those longer missions, he said. A new model costs about $150,000. Blue has sawtoothed up and down 60,000 times, and each time, a piston inside the glider moves the water in or out. Those parts wear out.

Gliders can study more than just weather, he said. On one mission, Blue carried an acoustic listening device for detecting fish. Right now, the glider is mapping what scientists call the "cold pool," the layer of water below the warm surface layer. The cold pool is an important habitat for fish and scallops, he said.

Goni said universities like UMass Dartmouth make an important contribution to glider research, and the glider project is ready to start making a bigger impact on hurricane forecasting.

"The difference between gliders and not gliders, it's dramatic," he said.

©2018 The Standard-Times, New Bedford, Mass. Distributed by Tribune Content Agency, LLC.