Posts Tagged ‘Gulf Stream’

UGA Skidaway Institute scientists study dynamic Cape Hatteras waters

April 5, 2016

 

Sometimes called the “graveyard of the Atlantic” because of the large number of shipwrecks there, the waters off of Cape Hatteras on the North Carolina coast are some of the least understood on the U.S. eastern seaboard. University of Georgia Skidaway Institute of Oceanography scientist Dana Savidge is leading a team, which also includes UGA Skidaway Institute scientist Catherine Edwards, to investigate the dynamic forces that characterize those waters.

The four-year project, informally called PEACH: Processes driving Exchange at Cape Hatteras, is funded by $5 million grant from the National Science Foundation. Skidaway Institute will receive $1.2 million for its part.

UGA Skidaway Institute scientists Dana Savidge (l) and Catherine Edwards

UGA Skidaway Institute scientists Dana Savidge (l) and Catherine Edwards

Two opposing deep ocean currents collide at Cape Hatteras, making the Atlantic Ocean near there highly dynamic. The warm Gulf Stream hugs the edge of the continental shelf as it flows north from the tip of Florida.  At Cape Hatteras, it opposes a colder current, the Slope Sea Gyre current, that moves southward along the mid-Atlantic coast and breaks away from the coast toward northern Europe. As in the deep ocean, the cool shelf waters of the mid-Atlantic continental shelf meet the warm salty shelf waters from the south at Cape Hatteras.

The convergence of all of these currents at one place means that, after long lifetimes in the sunlit shallow shelves, these waters may export large quantities of organic carbon—small plants and animals that have grown up on the shelf—to the open ocean. Scientists have little understanding of the details of how that happens and how it is controlled by the high-energy winds, waves and interaction the between the constantly changing Gulf Stream and Slope Sea Gyre currents.Cape Hatteras Project Map 2 w

According to Savidge, the area is very difficult to observe because the water is shallow, the sea-state can be challenging and the convergence of strong currents at one place make it hard to capture features of interest.

“It’s difficult to get enough instruments in the water because conditions change rapidly over short distances, and it’s hard to keep them there because conditions are rough,” she said. “Ships work nicely for many of these measurements, but frequently, the ships get chased to shore because of bad weather.”

To overcome the limitations of ship-based work, the research team will use a combination of both shore- and ocean-based instruments to record the movement and characteristics of the streams of water. A system of high-frequency radar stations will monitor surface currents on the continental shelf all the way out to the shoreward edge of the Gulf Stream, providing real-time maps of surface currents.

“Measuring surface currents remotely with the radars is a real advantage here,” Savidge said. “They cover regions that are too shallow for mobile vehicles like ships to operate while providing detailed information over areas where circulation can change quite dramatically over short times and distances.”

Edwards will lead a robotic observational component in which pairs of autonomous underwater vehicles called gliders will patrol the shelf to the north and south of Cape Hatteras.  Packed with instruments to measure temperature, salinity, dissolved oxygen and bio-optical properties of the ocean, both shelf- and deep-water gliders fly untethered through the submarine environment, sending their data to shore at regular intervals via satellite.

To compensate for the notoriously difficult conditions, Edwards will take advantage of a novel glider navigation system she developed with students and collaborators at Georgia Tech that automatically adjusts the glider mission based on ocean forecasts as well as data collected in real time.

“Our experiments show that we can keep the gliders where they need to be to collect the data we need,” she said. “The best part is that we get to put the maps of surface currents together with the subsurface information from the gliders, and we can make all of this information available in real time to scientists, fishermen and the general public.”

The researchers will also place a number of moorings and upward-pointing echo sounders on the sea floor. These acoustic units will track the water movement while also recording temperature and density.  PEACH will focus primarily on the physics of the ocean, but the information the researchers gather will also help scientists more fully understand the chemistry and biology, and may cast light on issues like carbon cycling and global climate change.

“Everyone is interested in the global carbon budget, and the effect of the coastal seas on that budget is not well understood,” Savidge said. “For example, many scientists consider the continental shelf to be a sink for carbon, because there is a lot of biology going on and it draws in carbon.

“However, 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 project will run through March 2020. The remaining members of the research team are Harvey Seim and John Bane of the University of North Carolina; Ruoying He of North Carolina State University; and Robert Todd, Magdalena Andres and Glen Gawarkiewicz from Woods Hole Oceanographic Institute.

 

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Scientists use underwater robots to excite students about science

March 3, 2014

Can underwater robots catch the imagination of middle and high school students and spark an interest in science, technology, engineering and mathematics? Researchers and educators from the University of Georgia’s Skidaway Institute of Oceanography and Marine Extension (MAREX) think so. They are creating an education program focused on autonomous underwater vehicles (AUVs), also called gliders or underwater robots.

The program, “Choose Your Own Adventure,” will capitalize on Skidaway Institute’s expertise with AUVs and MAREX’s extensive history of marine education. Skidaway Institute scientist and UGA faculty member Catherine Edwards, and MAREX faculty members Mary Sweeney-Reeves and Mare Timmons will direct the one-year project.

Catherine Edwards (center) demonstrates an AUV to Mary Sweeney-Reeves (left) and Mare Timmons.

Catherine Edwards (center) demonstrates an AUV to Mary Sweeney-Reeves (left) and Mare Timmons.

The AUVs are a cutting-edge technology in marine research. The torpedo-shaped vehicles can be equipped with sensors and recorders to collect observations under all conditions. They are launched into the ocean and move through the water by adjusting their buoyancy and pitch. Because they are highly energy-efficient, gliders can remain on a mission for weeks at a time. Every four to six hours over their mission, they surface, report their data by satellite phone and receive instructions as needed.

Skidaway Institute’s AUV, nicknamed “Modena,” has been used in several recent projects, including “Gliderpalooza,” a simultaneous, cooperative launch of 13 AUVs from different institutions in 2013.

“Gliders are education-friendly, but the existing outreach activities are stale,” said Edwards. “Our program will develop the next generation of AUV outreach programs by combining cutting-edge, interdisciplinary research with educational activities and strong STEM components.”

The proposed work will highlight the problem of working with the strong tides that are characteristic of the Georgia coast. A big issue in operating gliders there is developing a guidance and navigation system that will function well in that kind of environment. The fast-moving Gulf Stream, located roughly 100 miles off the Georgia beaches, also introduces navigation problems.

“Although the AUVs have Global Positioning Systems and can be programmed to travel a set course, tidal and Gulf Stream currents can exceed the glider’s forward speed, which can take the instrument off course and keep us from collecting data where we need it,” Edwards said.

However, on the education side, the predictability of tides makes the proposed program highly intuitive and education-friendly.

“Students who grow up and live on the water already have an intuitive sense of tidal currents,” said Timmons. “Students understand why currents change during certain phases of the moon. This coastal intuition will provide a foundation for us to start an innovative, hands-on approach to STEM activities.”

Activities will depend on grade level so middle school students will have different objectives than those in high school. However, all the activities will address the direction and speed the AUV travels to a destination. The AUV direction and speed will depend on the sea state of coastal waters such as strong currents, storms or high winds.

To address the problem of strong tides, Edwards and a team of Georgia Tech graduate students, co-advised by Fumin Zhang, have developed the Glider Environmental Network Information System, called GENIoS, which optimizes a glider’s path based on data from real-time observations and ocean models. Current doctoral students Dongsik Chang and Sungjin Cho are working to upgrade the system to integrate real-time maps of surface currents measured by Skidaway Institute radar systems.

The education plan is to involve two local educators, April Meeks and Ben Wells, who teach in the Savannah-Chatham County Public School System. Since the activities are multidisciplinary, their expertise in building math curriculum will be valuable as the team integrates concepts of marine science, math and engineering into classroom activities.

“After the initial planning phase, we will be taking the program on the road to Chatham County schools,” said Sweeney-Reeves.

Activities will include student role-playing as an AUV maneuvers through a playing field of vector currents on a large game board. Successful arrival at their destination depends on how the individual pilot responds to currents, wind and density changes in route.

“The real fun will begin when obstacles, like underwater volcanoes, a giant squid or other surprises, cause the pilot to reroute the course of the AUV,” said Sweeney-Reeves.

The activities will allow students to develop analytical skills in a program that will be compliant with Next Generation Science Standards for the 21st Century in the common core state curriculum.

The funded study will include two short glider deployments. A summer 2014 deployment will be used for field-testing, software validation and developing real-world scenarios for the outreach program. A fall deployment will serve as an opportunity for classroom participants to communicate with the glider in real time.

“We hope this one-year program will serve as a springboard for future funding and continued joint outreach by Skidaway Institute and Marine Extension,” said Edwards. “We’d love to develop computer games and apps for tablets and mobile phones that let students fly gliders through even more realistic scenarios based on the measurements we collect in real time.”

The program is being funded through a joint grant from Skidaway Institute, UGA Public Service and Outreach, and the UGA President’s Venture Fund. The UGA President’s Venture Fund is intended to assist with significant funding challenges or opportunities. The fund also supports small programs and projects in amounts typically ranging from $500 to $5,000.

For additional information, contact Catherine Edwards at 912-598-2471 or catherine.edwards@skio.uga.edu; Mary Sweeney-Reeves at 912-598-2350 or msweeney@uga.edu; or Maryellen Timmons at 912-598-2353 or mare@uga.edu.

 

Sea Turtle Release Video

December 11, 2013

Here is a video of the release Delta, the loggerhead sea turtle from the Tybee Island Marine Science Center. Delta was carried to the Gulf Stream on board the R/V Savannah as a “piggy back” on an already scheduled science cruise.

UGA Skidaway Institute assists in sea turtle release

December 5, 2013

Delta, a loggerhead sea turtle, spent the first 15 months of her life in an aquarium tank, but now she is swimming free in the Atlantic Ocean, courtesy of the UGA Skidaway Institute of Oceanography and its Research Vessel Savannah.

Delta was hatched on Tybee Island on August 19, 2012 as a straggler, a juvenile sea turtle that does not successfully leave the nest. She was taken to the Tybee Island Marine Science Center. There, she served as the Science Center’s Ocean Ambassador and educated more than 49,000 thousand visitor.

Eventually, though, Delta grew too large for her tank and it became necessary to release her into the wild. Although the Atlantic Ocean is only a few steps from Science Center’s front door, the water on the Tybee beaches is fairly cool this time of year. Delta’s caretakers at the Science Center wanted to release Delta into the warmer waters of the Gulf Stream. The Tybee Island Marine Science Center contacted Skidaway Institute for assistance. Conveniently, Skidaway Institute scientist Gustav Paffenhöfer had a similar research cruise on board the R/V Savannah scheduled for the coming weeks, and he agreed to allow Delta and her crew to “piggy back” on this trip.

 In preparation for her release into the wild, Delta was fed live crabs and jellies, which helped her bulk up to a healthy twelve pounds. Delta was also checked out by veterinarian Terry Norton from the Georgia Sea Turtle Center on Jekyll Island.

With Delta and her team of handlers aboard, the R/V Savannah left the Skidaway Institute dock on Monday morning, Dec. 2, for the ten hour cruise to the edge of Georgia’s broad continental shelf and the western edge of the Gulf Stream. Captain Raymond Sweatte identified a favorable release spot, approximately 82 miles southeast of Tybee Island, based on the location of the shelf edge and by monitoring the surface ocean temperature. At the point of release, the water temperature was approximately 80 degrees Fahrenheit.

Tybee Island Marine Science Center staffers Michael Partridge and Beth Palmer carry Delta in a basket for her release.

Tybee Island Marine Science Center staffers Michael Partridge and Beth Palmer carry Delta in a basket for her release.

As she is lowered over the side of the R/V Savannah, Delta starts to climb out of the basket.

As she is lowered over the side of the R/V Savannah, Delta starts to climb out of the basket.

Delta’s crew placed here in a plastic shrimp basket and lowered her off the R/V Savannah’s stern. Once in the water, Delta quickly emerged from the basket and swam out of sight.

Tybee may not have seen the last of Delta. “Since loggerhead sea turtles return to their natal beaches to nest, we can expect to see Delta back on Tybee around 2043,” said Cody Shelley from the Science Center.

 

UGA Skidaway Institute participates in Gliderpalooza 2013

September 18, 2013

More than a dozen underwater robotic vehicles called “gliders” will be launched simultaneously this month in a massive, cooperative project involving 10 east coast research institutions, including the University of Georgia Skidaway Institute of Oceanography. Dubbed Gliderpalooza 2013, the fleet of gliders will cruise the waters of the east coast for several weeks, collecting data that could help improve future hurricane forecasts. 

UGA Skidaway Institute scientist Catherine Edwards makes adjustments to the glider “Modena” while R/V Savannah crewman Mickey Baxley assists.

UGA Skidaway Institute scientist Catherine Edwards makes adjustments to the glider “Modena” while R/V Savannah crewman Mickey Baxley assists.

The gliders are torpedo-shaped vehicles, equipped with sensors and recorders to collect observations under all conditions. These autonomous underwater vehicles, or AUVs, move through the water by adjusting their buoyancy and pitch. Because they are highly energy efficient, gliders can remain on a mission for weeks at a time. Every 4 to 6 hours over their mission, they surface, report their data by satellite phone and receive instructions as needed.

According to Skidaway Institute scientist Catherine Edwards, one goal of Gliderpalooza 2013 is to test the feasibility of using a fleet of gliders to work together and to integrate their data—collected in the same time period, but over a wide geographical range.

“Gliders are powerful tools for oceanographers,” Edwards said. “We believe there is great potential to expand the value of them by working together on the deployments and integrating the data each collects.”

Another reason for promoting the use of gliders is their relatively inexpensive cost of operation. Gliders can operate for weeks at a time and in all kinds of weather conditions for a small fraction of the daily coast of an ocean-going research vessel.

“Gliders will never replace ships in oceanography—ship surveys are often the best way to collect data,” Edwards said. “But AUVs require far fewer resources and personnel than shipboard work, and can operate in conditions that would be impossible for traditional ship surveys. For lengthy data-collection missions, a glider can operate for pennies on the dollar by comparison.”

Scientists at Rutgers University are coordinating the project. Computers there will gather the data from the various glider groups, and make it available through a data assembly center for access to and visualization of the data in real time. Glider groups participating in Gliderpalooza will contribute pictures, updates and other notes of interest to scientists and the general public on a blog available at http://maracoos.org/blogs/main/

September was chosen as the month for deployment because many important fish species migrate in that month, and a coordinated experiment can provide a more complete picture of oceanographic conditions and fish populations. September is the most active month for hurricanes, and there is interest in the use of gliders to better understand the effects of major storms on the mixing and transport of heat, nutrients and material.

The Skidaway Institute glider, nicknamed “Modena,” and several others will also be equipped with a special instrument to monitor fish migration. In order to track fish migration, some fisheries biologists tag fish with an acoustic transmitter. The tag-transmitter sends out a sound signal identifying the fish. Typically, receivers on buoys and other stationary platforms monitor these signals. This will be the first time a fleet of moving gliders will be used to monitor fish migration.

Gliderpalooza will also serve as a field test of a new glider navigation system developed by Georgia Tech graduate students, Dongsik Chang, Klimka Szwaykowska and Sungjin Cho, who are supervised by Edwards and Georgia Tech collaborator Fumin Zhang.

Catherine Edwards works on Modena with her team of grad students.

Catherine Edwards works on Modena with her team of grad students.

Gliders can only receive GPS information at the surface. They navigate underwater by dead reckoning, using information on ocean currents from the last leg of their mission. However, the strong tidal currents on the Georgia shelf, combined with the fast-moving Gulf Stream at the shelf edge often exceed a glider’s forward speed. This creates the opportunity for significant navigational errors.

The Glider Environmental Network Information System (GENIoS) is an automated system that optimizes glider navigation based on real time data from ocean models, high frequency radar and measurements from the glider itself. By integrating these data with ocean models, GENIoS provides a more accurate prediction of the currents the glider will navigate through, and chooses the most efficient target waypoints for the glider to aim for as those currents change in space and time.   

During Gliderpalooza, the Skidaway Institute glider will conduct a triangle-shaped mission that includes one leg along the edge of the continental shelf, which also corresponds roughly to the western edge of the Gulf Stream.

“The combination of strong tidal currents and the influence of the Gulf Stream will serve as a strong test of the system,” Edwards said.

The collected glider data will go through NOAA’s National Data Buoy Center to the National Weather Service, the U.S. Navy and other data users for modeling. Data from the glider missions will also be public and available on the Integrated Ocean Observing System Glider Asset Map and at http://www.ndbc.noaa.gov/gliders.pahp.

Funding for Modena’s mission is provided by the UGA Skidaway Institute of Oceanography and the Southeast Coastal Ocean Observing Regional Association.

More information and an ongoing update on the progress of the project are available on the Gliderpalooza 2013 blog at http://maracoos.org/blogs/main/?p=448.

Glider-robots!

December 19, 2011

We had a real nice story on the front page of this morning’s Savannah Morning News. A big thanks to Mary Landers and her editors!

Skidaway Institute scientist discovers important new eddies off southeast US coast

December 16, 2010

Skidaway Institute of Oceanography professor Dana Savidge aims much of her research efforts towards observing the way ocean currents move in the Gulf Stream and across Georgia’s continental shelf. Those efforts have paid off in the discovery of a series of previously unidentified eddies which may have a significant influence on the way energy and material are transported between the Gulf Stream and the shelf waters.

Savidge’s findings were published in a recent issue of Geophysical Research Letters. Jonathan Norman from Armstrong Atlantic State University also contributed substantially to the analysis, along with several members of the Skidaway Institute team, including Trent Moore, Julie Amft and Catherine Edwards.

These researchers observed Shelf Edge Tide Correlated (SETC) eddies by using low-power, high-frequency radar systems that monitors surface ocean currents across the continental shelf and out into the Gulf Stream. The small, short-lived eddies spin up along the western edge of the Gulf Stream twice daily, as the tide turns. They move southwesterward, along the shelf edge — sometimes drifting towards shore — before dissipating two or three hours later.

In this graphic depiction of radar-derived coastal currents, the color, length and direction of the arrows represent the velocity of surface currents. The Gulf Stream is clearly evident in red and yellow. A Shelf Edge Tide Correlated eddy can be seen in the box on the left edge of the Gulf Stream.

According to Savidge, the importance of the SETC eddies lies in their influence on the Gulf Stream. “The Gulf Stream transports an incredible amount of heat and kinetic energy,” she said. “It has a strong influence on the global climate.”

In addition, fluctuations or meanders in the Gulf Stream’s flow pull nutrient-rich cold water from the deeper ocean and onto the shelf, providing a basic food source for marine life. The newly-discovered eddies apparently affect both those processes.

Skidaway Institute scientist Dana Savidge standing next to a research radar antenna.

“These are processes we didn’t know were happening that affect how the Gulf Stream transports heat and energy,” Savidge said. “This is information that must be put into a model if you want the model to accurately reflect what the Gulf Stream is doing in terms of transporting heat and energy.”

The nutrients from the deep ocean that the SETC eddies lift across the shelf edge and into the sunlit upper regions of the coastal ocean may contribute to phytoplankton growth, thereby potentially contributing resources for the shelf’s wider range of marine life.

“Similar eddies may occur along other continents where currents like the Gulf Stream exist, so it will be important to determine how important they actually are in the complex interaction between the Gulf Stream and the coastal waters.” Savidge said.

The research was funded with grants from the National Science Foundation and the National Oceanic and Atmospheric Administration (NOAA). The radars were purchased with funding from the Georgia Research Alliance and NOAA.

Skidaway scientist Dana Savidge promoted

July 28, 2010

Skidaway Institute of Oceanography researcher Dana Savidge has been promoted to associate professor.

Dr. Dana Savidge

A physical oceanographer, Savidge joined Skidaway Institute in 2003 as an assistant professor. Savidge studies Gulf Stream variability and ocean circulation, with projects on the continental shelves of Cape Hatteras, Georgia, and Antarctica. One key component of Savidge’s research is a shore-based radar system that measures surface ocean currents as far as 125 miles off the Georgia coast.

Savidge earned her bachelor’s degree in physics from Hanover College (Indiana) and her master’s degree in geophysics from Georgia Tech. Her doctorate in marine sciences is from the University of North Carolina at Chapel Hill.

Update From the Gulf Stream: No Tarballs or oil found in quick survey

June 28, 2010

Professor Jay Brandes wrote this report from a short research cruise to the Gulf Stream this past weekend.

This last Friday-Saturday, I had the opportunity to tag along with a group of 15 K-12 teachers and Dr. Marc Frischer, who was leading them on a cruise out to the Gulf Stream.  It was to be the highlight of a weeklong intensive workshop on ocean literacy for the teachers, and the first time that many of them had been on a ship out of sight of land.

R/V Savannah pulling away from the dock.

I came along to do a little preliminary reconnaissance for possible traces of oil and for plastics in the South Atlantic Bight region.

There has been a considerable amount of concern about oil being carried by the Gulf Stream / Loop Current (see previous posts) from the Deepwater Horizon Spill. While no satellite imagery or other data has suggested that large amounts of oil has reached the Gulf Stream, it is always possible that smaller amounts could have been carried into the current.

Thus it makes sense to take a look for oil traces. Given the timeframe of the cruise (leaving at 4 pm Friday, getting back at midnight Saturday night) there wouldn’t be enough time to conduct an exhaustive survey. However, there was enough time to do a few quick tows. In addition, I wanted to see how much plastic contamination might be out there. Most of us have seen the reports on the “great Pacific Garbage Patch”, and there is a lesser one out in the middle of the North Atlantic as well. But little data exists for out coastal waters.

Unlike the sheets of oil seen in the Gulf, the oil reaching our region is expected to be weathered and broken up into smaller pieces, called tar balls. If they are widely spread out, as expected, then the best and fastest way to collect them (or search for them) is to use what is called a “neuston” net. Neuston refers to organisms living at the sea surface. Such a net is designed be towed behind or beside the research vessel, right at the surface. Scientists also have used such nets to collect floating plastics in the ocean.

We conducted four surveys, towing our net for a half hour in the middle of the Gulf Stream, its edge, the outer shelf, and the middle shelf. We found no tar balls or other oil residues in any of the samples, which was a relief. While I have to caution that these were just small surveys (the net is only 2 meters wide by 1 deep), and it is a big ocean, the lack of any sign of oil is at least a positive sign.

Some of the Gulf Stream plastic

However, the same could not be said about plastics. We found small plastic pieces in all of our net samples, ranging from 1-2 mm size tiny particles to larger pieces a few cm across. One would not see these in looking out from a boat, unlike the big pieces found in the “garbage patches”. But they are of a size that will interfere with marine organisms, because they can be ingested.

Overall, the levels of plastics were low, and I feel that I can describe our offshore environment as relatively pristine, from this standpoint. It is up to all of us to keep it that way.

More on the oil spill and the Atlantic Coast

June 24, 2010

Earlier this month a group of experts from the institutions of the South Atlantic Sea Grant Program gathered at Skidaway Institute for a discussion of the Gulf of Mexico (GoM) oil spill and its potential effect on the Atlantic coast.

Here is an abbreviated summary of their conclusions.

Overall, the panel noted three distinct phenomena that must be considered:

(1) oil released at the Deep Horizon (DH) site and moving within the GoM, (2) oil in various forms that may be “captured” by the Loop Current and then transported into the Gulf Stream, and(3) the potential for oil in its various forms to move in a westerly direction from the Gulf Stream toward our nearshore waters and the southeastern coastline.

The experts agreed that there are some hard realities and major questions that limit even generalizing about the movement of spilled Gulf oil to South Atlantic waters. These include:

* Despite estimates by BP and federal agencies, the amount of oil that has spilled into the GoM is essentially unknown.  The actual volume of oil spilled there will affect the chances of it reaching South Atlantic waters.

*Authorities in the Gulf have no firm grasp as to where spilled oil – in its various forms and concentrations – can be found within the GoM’s water column and geographic expanse.  Where oil lies in the Gulf, and at what depth, could play a substantive role in its entrainment in and movement via the Loop Current.

* It is still highly speculative to pinpoint the location, depth, and amounts of GoM oil that might eventually be captured and transported by the Loop Current over specific periods of time. Understanding the sourcing, amount, and timing of spilled oil bleeding into this major GoM current is critical to understanding the oil’s possible ultimate transport to the southeastern U.S. region.

* Major questions exist about the nature of the spilled oil.  For instance, how much oil has dispersed or has been degraded?  How much will be degraded in coming weeks and months?  And what are the physical and chemical forms that such degraded oil will take (e.g., slicks, tarballs, underwater plumes, diluted at various concentrations, etc.).  Such degraded oil outcomes could affect how spilled oil will move.

At the same time, the panelists agreed that:

* Much is known about how general ocean circulation typically works in the GoM and South Atlantic Bight, due to our knowledge about the GoM’s Loop Current, the Atlantic’s Gulf Stream, and the interrelationship between them. There was unanimous agreement that the Loop Current and Gulf Stream would be the main “conveyor” of the Gulf oil should it move to South Atlantic waters.

* The first major step in any movement of Gulf oil to the South Atlantic would be its entrainment in the GoM’s Loop Current.  In recent weeks, the Loop Current has been “pinched” at its ox-bowed (loop) narrowing, creating an eddy separated from the Loop Current itself. This fluctuation, manifested as a separated eddy, has acted as a barrier to major movement of oil into the Loop Current.  Thus, that action may have prevented and delayed the movement of oil toward the Atlantic.  See an animated depiction of this eddy in relationship to the Loop Current here.

* The separated eddy now present in the Gulf, however, will either drift to the west (which is good), as it will take entrained oil with it, or reconnect to the Loop Current in the near future (not so good); the controlling factors being seasonal weather trends and events and perhaps other factors that are now poorly understood.  A more fully developed Loop Current resulting from re-attachment could reach farther north into the GoM and therefore closer to the spill zone center, likely capturing more oil in various forms and more fully channeling it toward the Florida Straits and possibly the Gulf Stream.

Once within the Loop Current, that oil could move from the GoM to the coastal waters off Cape Hatteras, NC in about a month’s time under typical weather conditions.

* Once oil borne by the Loop Current reaches the southeast end of the Florida peninsula, it then could become captured by the Gulf Steam and move to the north, offshore of the east coasts of FL, GA, SC, and NC.

* The risk of having oil spill residuals come ashore along the southeastern coast would be greatest along the southern portion of Florida’s east coast, due to the close proximity of the Gulf Stream to that shoreline.  Factors affecting the prospects and amounts of oil reaching the shoreline include shearing and eddy effects along the Gulf Stream’s west (inshore) edge, prevailing winds and their speeds, and acute weather events.

* A second area in the South Atlantic that would be at higher risk for oil spill residuals coming ashore is at North Carolina’s Cape Hatteras and neighboring Outer Banks beaches.  Again, this would be mainly driven by proximity of the Gulf Stream to the shore and weather events, but also by onshore eddies and jetting actions caused by interactions of the Gulf Stream near Hatteras with southerly flowing currents of cooler water from the north.

* Shorelines and waters between south Florida and Cape Hatteras also could experience visible oil deposits, diluted concentrations of oil, and other effects.  Manifestations of oil will likely be more highly dependent on acute weather events (significant coastal storms), prevailing wind direction and speeds over set periods of time, and seasonally-related perturbations (e.g., eddies, meanders, “spin-offs”) along the inshore (western) edge of the Gulf Stream.

* Due to the greater width of the continental shelf off of South Carolina, our shoreline and waters are less likely to be impacted by Gulf oil.  Deep hard-bottom reefs and fisheries would be more vulnerable in conjunction with upwelling of deep Gulf Stream waters associated with spin-off eddies, while coastal wetlands and estuaries would be the least vulnerable.

*The expert panel noted that the longer Gulf oil remains at sea, the more likely natural degradation of the oil could take place.  As such, it is possible that oil reaching south Florida waters may be in more visible forms (such as sheens, slugs, and tarballs); while oil that makes it to Hatteras waters may be more diluted and dissolved – and, if conspicuous at all, perhaps only be seen in forms such as water color/turbidity differences, thin oily residues on contact objects, and smaller tarballs.

The summit concluded with a brief discussion of secondary (but highly significant and concerning) effects of oil (and chemicals used as oil dispersants) reaching southeastern U.S. waters, which could include impacts on coastal fish, animal, and aquatic plant health, seafood contamination issues, and compromised coastal ecosystem functioning.  It could take years to observe, document, and experience these adverse effects.  Unfortunately, our coastal observation networks and infrastructure in and along the southeastern U.S. coastal waters and shorelines are currently inadequate to effectively monitor and measure such adverse effects in a timely manner.

As a result of the meeting, the four Sea Grant programs in the South Atlantic region will further develop a regional website regarding Gulf oil spill information, which can be found here.