News

Scientists studying the ocean currents that collide at Hatteras

These radar poles at the airport ramp transmit data on ocean currents. Photo: Pat Garber

For Ocracoke news, click here 

By Pat Garber

One afternoon in late March as I headed out the Airport ramp to the Ocracoke beach, I noticed a University of Georgia van parked nearby. A young man was taking cables out of the van and pulling them across the pavement.

Curious, I asked him what he was doing. His answer led me to contact Dr. Dana Savidge, the lead research scientist for a new study of the currents being undertaken at Hatteras Inlet. 

I detected the excitement in Dr. Savidge’s voice.

“I’ve been coming to Cape Hatteras most of my life, and I am intrigued by the way the water moves in this area,” she said. “There is no other place like it on the Atlantic coast. It is all happening here; everything important related to ocean currents, all in one place.”

Two major ocean currents collide at Cape Hatteras.

Here, the Gulf Stream, bringing warm water from the South, meets the Slope Sea Gyre, also called the Labrador Current, which Savidge describes as “a continuous ribbon of cold water from Labrador.”

The result is a dynamic exchange of inshore and offshore waters, not yet fully understood. Also at play are strong winds and unusual underwater topography.

Informally called PEACH (Processes driving Exchange at Cape Hatteras), the project will study the ocean currents to determine what causes the exchange between offshore and inshore waters.

The waters being studied have often been called the Graveyard of the Atlantic, home to many shipwrecks. This research project will help explain why.

PEACH will focus primarily on the physics of the ocean, according to Savidge, but the information gathered will also help scientists understand the chemistry and biology, and may cast light on issues like carbon cycling, global climate change and the feasibility of offshore drilling.

The project received a $5 million grant from the National Science Foundation, and the four-year project is ramping up now. Field work will continue until the fall of 2018.

 A variety of tracking systems will be used, including radar, buoys, moorings and gliders. Monitoring stations have been set up in the airport offices at Ocracoke and north of Frisco, and the data will be checked once a month

The cables I had observed are connected to poles which contain high-frequency radar equipment, situated on sand dunes overlooking the ocean.  With a range that extends 70 miles, they will monitor surface currents on the continental shelf all the way out to the shoreward edge of the Gulf Stream, providing real-time maps and detailed information over areas where circulation can change quite dramatically over short times and distances.

The research vessel “Armstrong” is setting out moorings, some of which will have floating net buoys attached to them, to measure wind, currents and density.

Especially intriguing are the gliders–six-foot-long autonomous underwater vehicles with wings that work in pairs to measure temperature, salinity, dissolved oxygen and bio-optical properties of the ocean.

They fly untethered through the submarine environment, floating or sinking based on momentary buoyancy, collecting data as they rise and fall and sending it to shore at regular intervals via satellite.

The project was conceived at the Skidaway Institute of Oceanography, which recently became part of the University of Georgia. Also involved are the University of North Carolina, North Carolina State University, Georgia Tech, the Coastal Studies Institute in Manteo and the Woods Hole Oceanographic Institute in Massachusetts.

“Everyone is interested in the global carbon budget,” Savidge said. “There are indications that the shelf south of Hatteras is both a sink and a source of carbon. This project may help clarify that picture.” 

The research will also be used to address ecosystems in this area that are home to many commercially important species, and may play a critical role in mitigating the spread of pollutants from potential future oil and gas extraction.

Sharing the research with the public is a priority, and there will be signs at the beaches, an exhibit and public presentations at the Graveyard of the Atlantic Museum in Hatteras, educational cruises and a website where the data can be accessed.

Categories: News

Tagged as: