Glider and Pumps Fight the Waves on a Stormy Monday
February 1, 2011 
9 Comments
Antarctica is renowned for having some of the fiercest weather on Earth. At any time of year, torrents of cold air can stream off the Antarctic continent and create vicious gales on the sea. So far we’ve been lucky to have calm seas and winds—especially on our visit to notoriously wind-whipped Cape Adare (see Jan 24 and Jan 25 posts).
Today we had just a touch of rough weather. By seafaring standards it was still nothing to worry about, but it did make us rearrange our plans to make sure none of our equipment ran the risk of being damaged. Read on through the slideshow to see what happened:
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- Bright sunlight like we had in January can be rare once you get away from the sea ice, according to Dr. Walker Smith. ‘Out in the ocean,’ he said, ‘I’ve gone for entire cruises without seeing the sun.’ This morning the winds were calm, but a rough 8-foot swell leaned against our ship, indicating there had been a storm off in the distance. Nearby, intense snow flurries swept briefly over us, like the ones in the clouds time-lapse we posted yesterday.
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- Along with the waves came petrels by the hundreds. At one point we had about 400 snow petrels and 250 Antarctic petrels riding banks of air off the ship, or sitting in groups that disappeared in rhythm as waves rolled through. Among these thin-winged birds flapped the steady brown bulk of a young southern giant petrel. Everyone asked me, since I’m a bird watcher, what the petrels might be eating here. But I didn’t know.
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- Despite the ominous waves, graduate student Dan Ohnemus of the Woods Hole Oceanographic Institution prepares to put particle pumps over the side (see Jan 20 post). It’s 6 a.m. and he and his adviser, Dr. Phoebe Lam, had been up all night processing samples from a previous location. As Dan tries to read serial numbers to Dr. Lam while upside down, he’s really leaning on his coffee.
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- Dan and marine technician Alan Shaw (left) hoist pumps over the side. They put six of these pumps at depths of up to 385 meters (1,078 feet) and left them to run for 3 hours. The yellow and orange cylinders at the top are the filters. They’re covered in plastic until just before they go underwater so they don’t collect any contaminating dust. The large dark device by Dan’s knee is a battery. It powers a pump (by Alan’s knee) that sucks seawater through the filters. Dan and Alan are kept safe from the heaving seas just a few feet away by the blue lines clipped to their safety belts.
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- Dr. Lam and Alan anxiously watch as waves push the ship while the pumps are working. Like many large ships, the Palmer has dynamic positioning—a system of computer-controlled thrusters that uses GPS information to keep the ship centered on a single spot on the ocean. This is normally a valuable tool in keeping a ship on station while time-consuming measurements are being made. But the waves had caused a heavy current that was pushing on the pumps and their winch cable.
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- With the current pushing and the ship staying put, the winch cable and pumps swung away from the ship like a pendulum. If the pumps swung too far they would tilt over and wouldn’t collect particles evenly. ‘That’s one thing my graduate adviser would always harp on,’ Dr. Lam said. ‘You have to keep your pumps level.’ So she asked Alan to radio the bridge and ask the captain to let the ship drift with the waves. After 2 hours, we ended up 2 miles away from where we had started. But Dr. Lam’s samples had collected evenly.
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- The glider team had planned to launch glider RU06 this morning, but the captain judged the swell a little too burly to risk putting the zodiac over the side. By evening the water had calmed a bit, so marine technicians Jeremy Lucke (steering) and Mark Harris (in the bow) set out with glider wrangler Eli Hunter, who is protecting the delicate glider as the boat charges down a wave face.
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- Back on the bridge at Glider Base, Dr. Josh Kohut and Ana Filipa Carvalho discuss the tests they’re putting RU06 through. This is the glider that had compass troubles on Jan. 28. The team recalibrated the compass during a trip to the sea ice on Jan. 30, and tests in the Aft Dry Lab (see yesterday’s post) showed it was working again. But better safe than sorry, so Dr. Kohut and Filipa designed a test mission to see if the glider could steer in a circle while it was underwater. Filipa is Portuguese and works in a lab at the University of the Azores (in the middle of the Atlantic Ocean). She met and began working with Dr. Kohut when his team was flying a glider from New Jersey to Spain.
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- Eli relies on a ‘Jacob’s ladder’ to board the Palmer as the swell carries the zodiac away from the ship and opens a gap of dark, cold water beneath him. In a moment the waves will shove the zodiac back against the hull, so Eli is wasting no time in climbing. The glider had passed its test mission, and it will stay in the water for the rest of our cruise. Its mission is to fly across a shallow bank that the team thinks has a role in forcing Modified Circumpolar Deep Water toward the surface. While we explore other parts of the Ross Sea, the glider will take two 120-mile trips across this bank, measuring water conditions for us.
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- I told Chris this is proof he’s a truly talented photographer: he can make one of the most graceful birds in the world look so clumsy. This snow petrel had spent part of the morning resting on the bow. It had just leaped into the air and is about to pull its legs up under its belly feathers. In about half a second, it will spread its long wings and return to life as a flying sword blade.
Seeing Chris’s snow petrel photos this evening reminded me of the question everyone had been asking—what do these birds eat? They seem to spend all their time flying. They sometimes sit on the water, but we rarely see them diving or dipping their heads into the water.
I asked Dr. Scott Fay, an ecologist from Temple University, what he thought about the question. He said he thought our readers could probably come up with some good ideas.
So tell us: What do you think snow petrels might eat? And what could you do to find out, using just materials that are on the ship? We have an idea, and we’ll tell you about it after we hear some ideas from you.
Read more in these related posts:
- Out Comes the Science Equipment (Jan 20)
- Looking Back, Looking Forward (Jan 28)
- Plants That Eat Food (Jan 30)
- Time-Lapse Tour of the Ship (Jan 31)
- Changing Weather Time-lapse Video
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