Marine

Ocean gliding robots used to study melting Antarctic sheet ice

Ocean gliding robots used to s...
Oceanographers run through a series of tests in preparation to deploy one of the ocean gliders (Photo: Caltech)
Oceanographers run through a series of tests in preparation to deploy one of the ocean gliders (Photo: Caltech)
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Oceanographers run through a series of tests in preparation to deploy one of the ocean gliders (Photo: Caltech)
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Oceanographers run through a series of tests in preparation to deploy one of the ocean gliders (Photo: Caltech)
One of the gliders is deployed to begin a two-month study of temperature, salinity and ocean currents (Photo: Caltech)
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One of the gliders is deployed to begin a two-month study of temperature, salinity and ocean currents (Photo: Caltech)

The use of "ocean gliders" for conducting research in oceanic conditions not ideal for regular methods has been catching on in the scientific community. Examples of this have been seen in the detection of endangered whales in the North Atlantic and a study of the Atlantic sturgeon. Researchers have now turned their robotic ocean helpers towards Antarctica, to study the rapidly-melting ice sheets on the coast of the western part of that polar land mass.

The bullet-shaped ocean gliders at the heart of the study are fascinating in that they have no propeller and are instead given motion by a battery-powered pump that changes their buoyancy. Fluid from the pump is moved into a compartment inside the glider, making it less buoyant so it can sink. When this fluid is then pumped into an external bladder, it rises to the surface. Wings on the 6-foot (1.8-m)-long device translate this lift into motion.

Caltech researchers, using the gliders, set out to understand how it is that warm water, considered the main factor causing the Antarctic ice to melt, is ending up near the coast of the otherwise very cold continent. By having the energy-efficient gliders remain at sea for months at a time to do extended data collection, they found that the warm water was being carried along by so-called ocean eddies, which are similar to storms in the atmosphere.

"Eddies are instabilities that are caused by ocean currents, and we often compare their effect on the ocean to putting a spoon in your coffee," said researcher Andrew Thompson. "If you pour milk in your coffee and then you stir it with a spoon, the spoon enhances your ability to mix the milk into the coffee and that is what these eddies do. They are very good at mixing heat and other properties."

One of the gliders is deployed to begin a two-month study of temperature, salinity and ocean currents (Photo: Caltech)
One of the gliders is deployed to begin a two-month study of temperature, salinity and ocean currents (Photo: Caltech)

These eddies, given their variable conditions and remote locations, were better suited to being studied by the gliders versus large ships, particularly over an extended period of time. The gliders were also more useful than satellite data collection, owing to the fact the warm water is not on the surface, and thus something the satellites could not detect.

Robotic gliders at work

Researchers dropped the gliders into the waters in January 2012. The gliders then spent the next two months moving up and down through the eddies off the Antarctic coast, collecting temperature and salinity data at different locations and depths, and occasionally surfacing to "call home" the collection information.The gliders observed that temperature and salinity, working together, create a situation whereby the warmest water is not on top, but actually sandwiched in the middle layers of the water.

"You can't just take measurements at the surface," said Thompson. "You actually need to be taking a look at that very warm temperature layer, which happens to sit in the middle of the water column. That's the layer that is actually moving toward the ice shelf."

The Caltech team next plans to add meteorological data to what’s collected from the gliders. They will also use the gliders in conjunction with a surface Wave Glider robot to study how air and water play together in a spot of ocean between the southern tip of South America and Antarctica, called the Drake Passage.

You can watch a brief video of how the gliders work below.

Sources: Caltech, Gentoo

Oceanographic Underwater Glider Animation

6 comments
Johan Smit
Ummm....did you mean growing ice sheet. We are experiencing all time record ice cover around this continent at this time. Clearly powers at be would only finance "declining ice sheets'
Mel Tisdale
@ Johan Smit
Try visiting http://www.skepticalscience.com/antarctica-gaining-ice.htm. If that article doesn't convince you, put Antarctic Ice into the search facility on sceptical science dot com and take your pick.
As you wake up from your fossil fuel industry induced coma, you might even get a whiff of the coffee as you do so.
Tom Lee Mullins
I have read that the arctic ice sheets are growing in size and the number of polar bears are increasing in numbers. if the antarctic is decreasing in size, it could be the arctic is increasing in size to compensate?
Stephen N Russell
Use this in temperate oceans & equip with "ice armor" to break ice IF warranted Map under ice formations for No Pole alone.
Catweazle
@ Mel Tisdale
Instead of taking your information from a crackpot alarmist site run by a failed cartoonist and his friends with a somewhat distasteful liking for dressing up as Nazi officers in their spare time (the abbreviation SS might give you a clue), perhaps you would be better to take our information from some more reputable authority, such as this, for example.
http://www.ncdc.noaa.gov/sotc/global-snow/
Rann Xeroxx
This all sounds good to me but the problem with the data is that after it is collected it is manipulated (corrected) for purposes to fulfill ones hypothesis instead of just following the data and allow it to form your theories.
http://www.c3headlines.com/2011/12/science-by-lubchencos-noaa-fake-global-warming-by-changing-historical-temperature-data.html
Face it, even warmest have to admit that if any scientist were to come out with a study that does not support AGW, they would be blacklisted, lamblasted, loose fellowships, not get published, grants would dry up, and be overall ridiculed.