Posted on behalf of Jane Qiu
Science journalist Jane Qiu is at the Palmer ecological research station on the Antarctic Peninsula, joining researchers investigating how climate change has affected the region in recent decades. Please check back for her dispatches from the bottom of the world.
Today is the day. Researchers from early morning boating trips say the swell is unusually mild at the three-kilometre boating limit of the Palmer ecological research station in western Antarctic Peninsula. Travis Miles’s eyes light up at the thought of launching a deep-water Slocum glider.
Miles, an oceanographer at Rutgers University, New Jersey, and his colleagues have been testing the glider’s sensors and vacuum seals for weeks. Now it is ready and the sea condition is right. The team rushes into inflatable boats, named Houston and Apollo 25, from which they will lower the bright-yellow Slocum glider RU25 into the Southern Ocean.
Less than two metres long and weighing about 50 kilograms, Slocum gliders are one of the newest and most important tools for Antarctic research. A type of submersible named after Joshua Slocum, the Canadian-American adventurer who accomplished the first solo sail around the world, they can be fitted with sensors for measuring temperature, salinity, oxygen concentration, ecosystem composition and water health down to 1,000 metres below the ocean surface.
The pre-programmed gliders move through water by changing their buoyancy, and surface every few hours to contact the central control system in Rutgers University, New Jersey, through satellites – when they also relay data and check for new instructions. Moving at about 25 kilometres a day, the submersibles are able to survey unchartered waters under extreme conditions for over a month.
The data collected by RU25’s attached sensors will shed light on how close the Antarctic Circumpolar Current gets to the peninsula coast, how much heat it transports, and how this could affect sea ice and the ecosystem, says Miles.
We bring the boats to a halt at the outer rim of the boating limit, southwest of Palmer. The sea is extremely calm – in contrast to the massive swell that characterizes the region. The scattered rafts of icebergs take the most unusual shapes and forms, as if in a futuristic sculpture exhibition. A dozen Adelie penguins line up on one iceberg. A hundred metres to the north, a humpback whale regularly emerges from the deep.
“We wouldn’t have hoped for a better condition,” says Miles. He picks up the satellite phone and gets in touch with technicians of the central control system at Rutgers.
Michael Garzio and Kaycee Coleman lower RU25 from Apollo 25. To test the glider’s buoyancy system, it is programmed to sink to tens of metres and then come up to the surface. So far, so good. Miles sends the deployment command – but as we are waiting for the glider to take off, the leak detectors send out warning signals.
“It seems that we have a problem,” says Miles. RU25 has to be brought back to the lab for forensic examination. “That’s science,” he says. “I am sure we will get there eventually.”
Such glitches highlight the difficulties of using underwater vehicles in extreme environments. Earlier this year, two out of three gliders on the annual cruise of the Palmer Long-term Ecological Research (LTER) programme – set up by the US National Science Foundation twenty years ago to study the effects of environmental changes – never got launched at all due to leaks.
In this year’s research cruise, which will kick off early next month, a fleet of gliders carrying various optical and acoustic sensors will flex their muscles in the harsh waters of the Southern Ocean.
In the past 20 years, the LTER cruises have collected about 5,000 vertical profiles of the ocean along western Antarctic Peninsula – one of the world’s most extensive regional marine records. Merely five glider deployments in recent years, however, have generated four times that amount of data in a matter of weeks, says Oscar Schofield, an oceanographer also at Rutgers and head of the glider team. “The maturing glider technology promises to revolutionise oceanographic research.”
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Probing ocean acidification
Picture credit: Jane Qiu