Posts Tagged ‘autonomous underwater vehicle’

UGA Skidaway Institute receives funding for regional glider network

July 1, 2016

University of Georgia Skidaway Institute of Oceanography researcher Catherine Edwards is leading a team that has received a five-year, $750,000 grant from the Southeast Coastal Ocean Observing Regional Association, or SECOORA, to establish a regional glider network.

Also known as autonomous underwater vehicles, the gliders are torpedo-shaped crafts that can be packed with sensors and sent on underwater missions to collect oceanographic data. 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.

UGA Skidaway Institute of Oceanography researcher Catherine Edwards assembles the tail cone assembly of a glider.

UGA Skidaway Institute of Oceanography researcher Catherine Edwards assembles the tail cone assembly of a glider.

The team will work collaboratively to operate regular glider missions on the continental shelf in an area from North Carolina to Florida known as the South Atlantic Bight. Regular coordinated experiments will involve simultaneous deployment of gliders at multiple locations off Florida, Georgia and North Carolina. Sensors on the gliders will allow the team to map temperature, salinity, density, dissolved oxygen and other scientific data over the entire South Atlantic Bight. The data will help scientists understand ocean processes and how the ocean physics may affect fisheries—for example, the location of fronts or areas of increased productivity where fish often congregate.

“This glider observatory is the first time regular glider efforts have been funded in the South Atlantic Bight and is complementary to larger SECOORA efforts in observing and modeling,” Edwards said. “The work is highly leveraged by contributions from each of the team members and partnerships with fisheries and observing groups at the National Oceanic and Atmospheric Administration and NASA.”

Edwards and her team have designed the deployments with input from fisheries management partners and interests of commercial and recreational fisheries. Gliders will also be outfitted with passive and active acoustics receivers that will record sound and measure signals from tagged fish.   Fisheries managers at Gray’s Reef National Marine Sanctuary, state Department of Natural Resources offices, the South Atlantic Fisheries Management Council and others will be able use this information to better understand the ocean “soundscape,” fish migrations and key species use of their habitat.

“The glider missions will contribute important information related to research underway at Gray’s Reef,” said Sarah Fangman, superintendent of Gray’s Reef National Marine Sanctuary. “We have been studying fish movement patterns inside the sanctuary, and the gliders’ acoustic receivers will provide a valuable new tool to expand where we can observe fish movements.”

In addition to regular coordinated experiments with multiple gliders and maximum regional coverage, the project will leverage opportunities to develop regular transects in areas where glider data may be of interest, for example near marine protected areas like Gray’s Reef National Marine Sanctuary and other critical habitat zones designated by the South Atlantic Fisheries Management Council.

The glider data will provide valuable information for validation of ocean models—regional models of ocean circulation funded by SECOORA as well as the larger modeling community. Further, the data will be packaged and used to improve ocean model forecasts.

“We’re sending all of the glider data to the National Glider Data Assembly Center as it comes in so that it can be assimilated into the U.S. Navy’s operational models,” Edwards said. “The gliders will improve Navy forecasts on the fly with real time data.”

The remainder of the research team includes Chad Lembke from the University of South Florida, Ruoying He from North Carolina State University, Harvey Seim from the University of North Carolina and Fumin Zhang from the Georgia Institute of Technology.

Data and maps from the project will be shared freely and made available to the research community, fisheries managers and other stakeholders and the general public in near-real time through SECOORA at http://secoora.org/ and the National Data Buoy Center.

Advertisements

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.

 

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.

Skidaway Institute, Georgia Tech-Savannah partner on phytoplankton research

April 18, 2011

Sometimes scientific advances provide answers, and sometimes, they simply present more questions. That is what happened when scientists began using satellite imagery to study the ocean.

When Skidaway Institute of Oceanography scientists Jim Nelson and Catherine Edwards looked at satellite imagery of the ocean off the Carolinas, they noticed persistent blooms of phytoplankton, an important part of the marine food web. These mysterious blooms occurred during the winter along edge of the continental shelf off Long Bay — located between Cape Romain, South Carolina and Cape Fear, North Carolina. Phytoplankton blooms like those observed off Long Bay can provide a considerable boost to the bottom of the food chain, with significant implications for fisheries.

“The immediate cause of the blooms is an input of nutrients, like nitrogen and phosphorous, associated with transport and mixing of deep, cold onto the continental shelf,” said Edwards. “The Long Bay blooms persist for weeks or even months during the winter, suggesting multiple modes of nutrient input.”

Two of the guiding questions are why this feature is so persistent over the winter, and what are the dynamics that sustain this bloom?

Edwards and Nelson are teaming with Harvey Seim from the University of North Carolina and Fumin Zhang from Georgia Tech-Savannah on a project to answer those questions. The project is funded by a $1.6 million grant from the National Science Foundation supporting a team of scientists from all three institutions. With the help of Skidaway Institute research coordinators Trent Moore, Julie Amft and Charles Robertson, the project team will deploy moored and mobile instrument packages and conduct shipboard surveys to test hypotheses of how the winter blooms are formed and sustained.

The team will use some cutting-edge technology that will enhance its ability develop a clear picture of what is happening. This includes instrument packages mounted on moorings; mobile, autonomous “gliders”; underway ship surveys; standard ship-based station sampling; and satellite measurements of sea surface temperature and ocean color.

Skidaway Institute researchers (l-r) Catherine Edwards, Trent Moore, Julie Amft and Jim Nelson examine a glider.

Three moored packages will be deployed to provide continuous measurements of water properties and currents through the winter months. One mooring will be placed at 35 meters of depth, the approximate position of the shoreward edge of the winter bloom.

Two more packages will be placed in approximately 75 and 150 meters of water, with the 75 meter mooring equipped with an instrument package called a SeaHorse. Powered by wave motion, the Seahorse moves up and down its mooring wire, taking measurements throughout the water column. A telemetry system in the surface mooring periodically reports its observations.

The research team will also use another high-tech tool, autonomous underwater vehicles, also called gliders.

Skidaway Institute researchers lower a glider into a tank of water to adjust buoyancy and trim. (l-r) Trent Moore, Dongsik Chang, Charles Robertson and Julie Amft

Two of these torpedo-shaped vehicles, equipped with sensors and recorders, will provide the ability to collect observations under all conditions, including during winter storms when ship operations are not possible. The gliders will survey across the study area, taking and recording measurements as they go. From time to time over the four to five week missions, they will surface, report their data by satellite phone and receive instructions as needed.

The gliders will be controlled from shore with an autonomous glider control system co-developed by Fumin Zhang at Georgia Tech Savannah. Two Georgia Tech-Savannah graduate students, Klimka Szwaykowska and Dongsik Chang, are developing algorithms to optimize the glider sampling given real-time data collected by satellite, the SeaHorse profiler and the gliders themselves.

Catherine Edwards (r) and Dongsik Chang work on the tail of a glider while Klimka Szwaykowska looks on.

Members of the research team will spend much of the winter of 2012 aboard the Skidaway Institute research vessel R/V Savannah, conducting experiments and collecting data.

Armed with a better understanding of the physical processes that “fertilize” the outer shelf and how phytoplankton take advantage of the nutrient input, the research team will be able to answer larger questions about how biology and physics interact in Long Bay.

The project will run for three years.