Tag Archives: glider

UGA Skidaway Institute, SECOORA christen new glider

Researchers from the UGA Skidaway Institute of Oceanography and the Southeast Coastal Ocean Observing Regional Association (SECOORA) welcomed a new glider to their research fleet with a christening ceremony at UGA Skidaway Institute on Tuesday, April 23. The new glider was purchased and is owned by SECOORA, but will be based at UGA Skidaway Institute and operated by the UGA Skidaway Institute glider team headed by Catherine Edwards.

Gliders are torpedo-shaped crafts that can be packed with sensors and sent on underwater missions to collect oceanographic data, and are classified as autonomous underwater vehicles, meaning that they operate untethered on their own. Equipped with satellite phones, the gliders surface periodically to transmit their recorded data and to receive new instructions during missions that can last from weeks to months.

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The glider is named Franklin, after Benjamin Franklin, who ordered the first chart of the Gulf Stream.

The christening ceremony, based on traditional versions for naming and renaming boats, called upon the favor of the gods of the sea, the wind, the tide and the Gulf Stream, and was offered by Edwards, research professional Ben Hefner, SECOORA executive director Debra Hernandez and UGA Skidaway Institute assistant director Marc Mascolo.

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Catherine Edwards raises a glass to Franklin.

Hernandez then capped the ceremony by smashing a bottle of champagne against a metal weight positioned near Franklin’s nose.

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Debra Hernandez completes the ceremony.

Franklin is outfitted with a pumped conductivity-temperature-depth sensor and a three-channel fluorometer that measures chlorophyll, dissolved organic matter and turbidity. It also has a dissolved oxygen sensor and two built-in Vemco acoustic receivers that listen for tagged fish and other animals. The glider is powered by lithium-ion batteries that will allow it to remain on mission for up to five to six weeks at a time without recharging.

Franklin’s first deployment was a SECOORA mission at Gray’s Reef National Marine Sanctuary. It was joined on the mission by UGA Skidaway Institute’s other glider, named Angus.

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UGA Skidaway Institute gliders improve hurricane predictions

The models hurricane forecasters use to predict the paths of storms have become much more accurate in recent years, but not so much the models’ ability to accurately predict a storm’s intensity. Now, underwater gliders, operated by researchers at the University of Georgia Skidaway Institute of Oceanography, are part of a national effort to use marine robots to improve the accuracy of storm forecast models.

UGA Skidaway Institute research technician Ben Hefner launches a glider into the ocean. Photo courtesy MADLAWMEDIA

Two storms from the 2018 hurricane season provide examples of how quickly storm intensity can change. Hurricane Florence was predicted to be a Category 5 storm, but she weakened significantly before making landfall in North Carolina as a Category 1 storm on September 14. On the other hand, a month later, Hurricane Michael grew from a Category 1 to a Category 5 storm in just two days and hit the Florida panhandle on October 10.

Hurricanes feed off of heat from warm ocean waters like that found in the Caribbean, and in the Gulf Stream and shallow waters off the southeast United States, known as the South Atlantic Bight. This can be a tremendous source of energy for developing storms. Heat is transferred between the ocean and atmosphere at the ocean’s surface, but it is important to understand the amount of subsurface heat as well.

“Places where warm waters near the surface lie over cooler water near bottom, winds and other factors can mix up the water, cooling the surface and limiting the heat available to the atmosphere,” UGA Skidaway Institute researcher Catherine Edwards said. “Satellite data provides a nice picture of where the surface ocean is warm, but the subsurface temperature field remains hidden.”

UGA Skidaway Institute researcher Catherine Edwards examines the tail assembly of a glider.

This is where autonomous underwater vehicles, also known as gliders, can collect valuable information. Gliders are torpedo-shaped crafts that can be packed with sensors and sent on underwater missions to collect oceanographic data. The gliders measure temperature and salinity, among other parameters, as they profile up and down in the water. Equipped with satellite phones, the gliders surface periodically to transmit their recorded data during missions that can last from weeks to months.

“This regular communication with the surface allows us to adapt the mission on the fly, and also process and share the data only minutes to hours after it has been measured,” Edwards said. “By using a network of data contributed by glider operators around the world, the U. S. Navy and other ocean modelers can incorporate these data into their predictions, injecting subsurface heat content information into the hurricane models from below.”

The 2018 hurricane season provided Edwards and her colleagues a fortuitous opportunity to demonstrate the value of glider data. Edwards deployed two gliders in advance of Hurricane Florence. One was launched off the North Carolina coast and the other further south, near the South Carolina-Georgia state line. The gliders discovered the models’ ocean temperature forecasts were significantly off target. Edwards points to charts comparing the predictions from ocean models run in the U.S. and Europe with the actual temperatures two days before Florence made landfall.

On the south side of the storm path, the models predicted that the ocean had a warm, slightly fresh layer overtopping cooler, saltier water below, but the glider revealed that the water column was well-mixed and, overall, warmer and fresher than predicted. On the north side of the storm, the models predicted warm, well-mixed water, but the glider detected a sharp temperature change below the surface, with a much cooler layer near-bottom. However, the most surprising part was just how stratified the water was.

“There is almost a 14-degree Celsius (approximately 25 degrees Fahrenheit) error that the glider corrects in the model,” she said. “The model and data agree near-surface, but the models that don’t use the glider data all miss the colder, saltier layer below. The model that incorporated glider data that day is the only one that captures that vertical pattern.”

Not only can gliders provide a unique view of the ocean, they fly on their own, reporting data regularly, before, during and after a hurricane, making them a powerful tool for understanding the effects of storms.

“The glider data is being used in real time,” Edwards said. “These real time observations can improve our hurricane forecasts right now, not just in a paper to be published a year from now.”

Edwards and collaborator Chad Lembke, at the University of South Florida, had a third glider deployed in August before Florence as part of a glider observatory she runs for the Southeast Coastal Ocean Observing Regional Association (SECOORA). While it was recovered about a little over a week before Florence made landfall, the glider helped define the edge of the Gulf Stream, which is an essential ocean feature that is very hard for models to get right.

“So it’s possible that the data from that glider already improved any tropical storm predictions that use ocean models and take that glider data into account, because the Gulf Stream is so important in our region,” Edwards said.

Edwards works with colleagues from other institutions through SECOORA. Together they are making plans for the 2019 hurricane season. Funded by a $220,000 grant from the National Oceanic and Atmospheric Administration, they plan to pre-position a number of gliders in strategic locations to be ready for deployment in advance of incoming storms.

“Gliders are like the weather balloons of the ocean,” Edwards said. “Imagine how powerful a regular network of these kinds of glider observations could be for understanding the ocean and weather, and how they interact.”

Glider partners come to the rescue during Hurricane Irma

Hurricane Irma presented an interesting problem to UGA Skidaway Institute scientist Catherine Edwards and other glider operators in the Southeast. They had several autonomous underwater vehicles or “gliders” deployed off the east coast as the hurricane approached, including Skidaway Institute’s glider, “Modena.” Edwards and the others were confident the gliders themselves would be safe in the water, but the computer servers that control them would not.

Catherine Edwards works on “Modena.”

The gliders are equipped with satellite phones. Periodically, they call their home server, download data and receive instructions for their next operation. It was expected that Skidaway Institute would lose power for at least several days (as did happen). However, Skidaway’s backup server partner at the University of South Florida’s marine science facility in St. Petersburg, Fla. was also directly in the storm’s projected path.

“In the week before she hit, Irma sort of blew up our hurricane emergency plans,” Edwards said.

Several other options, including Teledyne Webb’s back-up servers and Rutgers University were not feasible for technical reasons. Glider operators at Texas A&M University came to the rescue. Catherine was able to instruct “Modena” to switch its calls over the Texas A&M server. No data was lost and “Modena” continued its mission.

According to Edwards, two big lessons emerged from the experience.

“First, most of us rely on nearby or regional partners for emergency and backup support, but disasters are regional by nature, and the same Nor’easter or hurricane can take you down along with your backup,” she said. “Second, there aren’t a lot of glider centers that can absorb several gliders on a day’s notice, and there are some compatibility and operations issues involved, so it is best to identify our potential partners and build out these steps into our emergency plans well in advance.”

UGA Skidaway Institute scientist shares Gulf oil spill research grant

UGA Skidaway Institute of Oceanography scientist Catherine Edwards is part of a research team that has received an $18.8 million grant to continue studies of natural oil seeps and track the impacts of the BP/Deepwater Horizon oil spill in the Gulf of Mexico ecosystem.

A satellite view of the Deepwater Horizon oil spill

A satellite view of the Deepwater Horizon oil spill

Known as ECOGIG-2 or “Ecosystem Impacts of Oil and Gas Inputs to the Gulf,” the project is a collaborative, multi-institutional effort involving biological, chemical, geological and chemical oceanographers led by the University of Georgia’s Samantha Joye. The research team has worked in the Gulf since the weeks following the 2010 Macondo well blowout.

The three-year, $18.8 million ECOGIG-2 program was funded by the Gulf of Mexico Research Initiative, or GoMRI.

“Our goal is to better understand the processes that have affected the oil spill since 2010,” Edwards said. “How the droplets were dispersed? Where the oil went? How it was taken up by small microbes and also the effects on animals further up the food chain?”

Edwards’ role in the project is to use autonomous underwater vehicles, also called “gliders,” to collect data on conditions around the spill site. Equipped with sensors to measure characteristics such as depth, water temperature, salinity and density, the gliders can cruise the submarine environment for weeks at a time, collecting data and transmitting it back to a ship or a shore station.

Skidaway Institute scientist Catherine Edwards adjusts a glider’s buoyancy with graduate students Sungjin Cho and Dongsik Chan.

Skidaway Institute scientist Catherine Edwards adjusts a glider’s buoyancy with graduate students Sungjin Cho and Dongsik Chan.

“We want to understand the ocean currents—how they change over time and how they change in depth,” Edwards said. “Surface measurements give us a two-dimensional picture of the ocean. Glider data in the vertical provides more valuable information for more fully understanding ocean currents and how they arise.”

The gliders will operate in conjunction with shipboard instruments and also independently. One advantage of using the gliders is they can operate during storms and rough weather, when it may not be possible to use ships. Edwards said shipboard work doesn’t always give a full picture of ocean dynamics simply by the fact that they can only go out when the weather is reasonably clear.

When working in conjunction with research ships, the gliders can provide additional observations, significantly improving the quality of the data set. The gliders also report dissolved oxygen concentrations and optical measurements of chlorophyll and organic matter, and may also be used as a test vehicle for new instruments in development.

Edwards will use “GENIoS,” a new software package, to help navigate the gliders. GENIoS uses high-resolution forecast models of wind and ocean currents, along with information from the glider itself, to calculate the optimal path for the gliders. This will improve the quality of the scientific data collected.

GENIoS is a collaboration among Edwards, Fumin Zhang from the Georgia Institute of Technology and their two Georgia Tech Ph.D. students, Dongsik Chang and Sungjin Cho. GENIos has been tested for more than 210 glider-days on the continental shelf off Georgia and South Carolina. This experiment will be its first test in the Gulf of Mexico.

Edwards also hopes to use this project to test the gliders as platforms for new, experimental sensors developed by other members of the ECOGIG-2 team.

Others involved in ECOGIG-2 include UGA marine sciences faculty Christof Meile, Renato Castelao and Catherine Edwards as well as Annalisa Bracco and Joe Montoya of Georgia Tech.

For additional information, contact Catherine Edwards at (912) 598-2471 or catherine.edwards@skio.uga.edu.