UGA sending Salty Dawg undersea

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UGA sending Salty Dawg undersea

RENATO CASTELANO

UGA will launch its first robotic submersible later this year, joining a growing number of research institutions that use the efficient and cost-saving instruments to explore the oceans.

UGA physical oceanographer Renato Castelao and colleague Ruoying He of North Carolina State University will launch two autonomous underwater vehicles called gliders in fall 2013. UGA’s Salty Dawg and NCSU’s Salacia, named for the Roman goddess of salt water, will remotely collect data on the exchange of water between the coastal ocean off Georgia and the Gulf Stream.

The Gulf Stream is a powerful ocean current that runs from Florida up the Eastern Seaboard and across the Atlantic Ocean. Along its route it influences fish and shellfish populations, weather and even ship fuel usage. Tendrils of the current, known as eddies, shear off from the Gulf Stream and move from the deep ocean toward the continental shelf, which extends for miles under water from the shore. The eddies, which are colder and saltier than the more shallow coastal waters and carry many nutrients, are thought to provide a major food source for marine life.

The six-foot glider, which looks like a torpedo with fins, moves forward when the nose cone fills with seawater, causing it to sink at an angle. At the desired depth, the glider discharges the water and slants upward again toward the surface, where the action is repeated. The speed is slow but steady, about 12 to 15 miles daily in an up-and-down, saw tooth pattern. As it rises and falls, the instrument-packed glider samples seawater at different depths and sends reports to a laboratory via satellite, where researchers download the data and monitor the vehicle’s progress. Except for launch and recovery, researchers stay on dry land.

Using a $775,616 grant from National Aeronautics and Space Administration, Castelao and He are first mapping the eddies using data from NASA satellites. Once mapped, the researchers will launch the gliders to measure the properties of seawater in and near the eddies. They will analyze water at different depths for temperature, salinity, chlorophyll, dissolved organic matter, light and oxygen levels, and the speed of the currents. The measurements will be correlated with the satellite data to provide a more detailed picture of eddy activity. Knowing where water temperatures and salt levels occur is useful for fishermen, because different species of fish prefer different habitats. The information will help fishermen reduce catches of unwanted species and lower fuel costs.

The Salty Dowg can run for weeks or months without returning to shore through the use of an energy-efficient electrical power system.