Ocean scientists can now plunge into the middle of the sea without leaving their offices.
Two-metre, 45kg, underwater gliders are swimming the oceans of the world and dutifully sending data home on everything from whale calls to the massive waves produced by hurricanes.
”The ability to be in the ocean all the time and do it over a sustained period — people are doing it now. And this is revolutionary,” said Oscar Schofield, professor at the Institute of Marine and Coastal Science at Rutgers University.
The gliders suck in and shoot out water to change their buoyancy and move up and down. Small wings on their missile-like bodies create lift to move horizontally.
Without a noisy propeller or engine, the gliders run silently and on very little power. A small battery pack can keep them gathering information 24 hours a day on month-long missions. They can also be programmed to surface and send data to land-based labs via satellite.
And while cost for a large research vessel can mount up at $15 000 per day, a single, reusable glider costs about $25 000.
Though the idea of such a device had been dreamed of for half a century, the winged gliders have only come into more common use in the past three years.
Five years ago very few scientific labs had even one of the gliders. Today as many as 15 labs across the country have up to 20 each to deploy on projects from the Mediterranean Sea to just off the New Jersey coast, Schofield said.
Several ocean scientists reported on the use of underwater gliders at the biannual ocean sciences meeting this week sponsored by the American Geophysical Union.
In October, scientists on the North Carolina coastline used a glider called Pelagia, from the Greek word for ”open ocean,” to gather data on physical and biological changes beneath the waves a few kilometres off Wrightsville Beach.
Earlier last year, two ships and 25 scientists from Rutgers, Columbia University and the University of Massachusetts-Boston used an underwater glider to follow two dye releases from the mouth of the Hudson River over two weeks. The project followed pollutants and other material discharged from the river to see how it interacts with the Atlantic Ocean.
Relatively light, easy to deploy and inexpensive, the gliders are not subject to violent surface conditions and have the ability to meander among sea creatures and ply the oceans in any weather, including hurricanes.
Mark Baumgartner, a scientist with the Woods Hole Oceanographic Institution, uses the gliders to observe whales.
The standard technique for watching the mammals involves using high-powered binoculars from the deck of a ship to spot them as they surface for air. But this method requires a lot of people and money, and is limited to times when conditions are clear, bright and calm.
”Some days when it’s good daylight but heavy seas, this becomes a very nauseating process to look through very large binoculars through a rolling ship,” Baumgartner said.
In May, Baumgartner’s team used a glider to capture the soulful calls of a humpback whale off the coast of Cape Cod, despite a storm that whipped up five metre seas and more than 30 knot winds during the five-day project.
Eric Terrill, director of the Coastal Observing Research and Development Centre at the Scripps Institution of Oceanography, is exploiting the gliders’ stamina in an attempt to better understand what fuels and changes the intensity of devastating hurricanes.
Working with the National Oceanic and Atmospheric Association on a project sponsored by the Office of Naval Research, Terrill’s team has dropped the machines off ships and parachuted them from 450m off planes in the path of storms.
Sensors attached to the undersea gliders measure salinity, water temperature to 200m, and the height of the soaring waves created by the storms. By recording the sounds of the waves as they break, researchers are also hoping to find a new way to measure the speed of a storm’s winds, he said.
”This is kind of adults playing lawn darts. What we would do is look at the forecast track of a storm … and so we would use the C-130 airplanes to actually air-deploy the packages in a gridded pattern in the path of the oncoming storm,” he said.
Terrill said researchers were surprised when the nine gliders they sent into Hurricane Francis in 2004 continued to send information back to shore even at the height of storm that had winds topping at 217kph.
The gliders weren’t used during the more recent Hurricane Katrina.
But Scripps is working with NOAA to look at the 2004 data to help them improve their models for predicting storms’ behaviour.
Schofield uses the gliders to work on forecasting toxic ”red tides” of algae off Florida and algae blooms and sediment movements off New Jersey.
In September a red tide prompted beachgoers in southwest Florida to complain of allergy-like symptoms while also causing local fish kills and closing oyster harvesting areas.
In the future information from the gliders will probably be combined with data from other technologies, such as satellites and radar, to create three-dimensional views of the ocean, Schofield said.
For now the gliders can help scientists better narrow down and target when and where they need to actually board a ship to get the information they want, he said.
”The big push … now that they’re starting to demonstrate their capabilities is to start getting them out there to be a permanent presence in the ocean,” he said. – Sapa-AP