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Current Events off AntarcticaGraduate student helps discover a previously unknown ocean current |
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| Enlarge ImageThe newly discovered Antarctic Peninsula Coastal Current (APCC) hugs the west coast of the 745-mile-long peninsula. Its waters may inject nutrients and juvenile krill from Marguerite Bay into the much larger Antarctic Coastal Current (ACC) to feed waters farther away. (Carlos Moffat, Woods Hole Oceanographic Institution) |
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| Enlarge ImageMIT/WHOI Joint Program graduate student Carlos Moffat used an instrument called a CTD rosette to measure temperature, salinity, and other water characteristics on a 2005 research cruise aboard R/V Revelle that started in Tahiti (16°S). (Courtesy of Carlos Moffat, Woods Hole Oceanographic Institution) |
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| Enlarge ImageBy the time the six-week cruise ended in the Southern Ocean (71°S), Moffat had put away his shorts and was seeing icebergs. (Courtesy of Carlos Moffat, Woods Hole Oceanographic Institution) |
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The scientific method can divert researchers down curious pathways.
Human psychologists study mouse brains. Astrophysicists look for cosmic
particles deep in mine shafts. Taxonomists trace bird evolution by
studying feather lice.
Carlos Moffat’s scientific career took a similar detour. Fascinated by
marine biology, he became a physical oceanographer to understand the
ways ocean water moves, mixes, and nourishes life at the bottom of the
marine food chain.
“I am one of those kids that spent a lot of time looking at ants and
stuff,” Moffat said. But after studying biology at the University of
Concepción, Chile, “I remember having the MIT/WHOI Joint Program
application in front of me and I had to decide between biological or
physical oceanography. I realized to be a good biological oceanographer
requires understanding physics."
Not long afterward, Moffat helped discover an ocean current that even
in the 21st century had remained unknown to humankind. It’s
understandable why it took so long. The newfound current flows south
along the west coast of the Antarctic Peninsula, a 745-mile (1,200-kilometer) spit
of ice and mountains that stretches north toward the Drake Passage and
Tierra del Fuego.
About halfway along the peninsula, the current dips into Marguerite
Bay, a vibrant nursery for the shrimplike krill that feed most of the
Antarctic’s animal life. Some scientists speculate that the newly
named Antarctic Peninsula Coastal Current may help sustain the
biological smorgasbord of krill, Antarctic cod, penguins, leopard
seals, and
whales in the Southern Ocean that surrounds the icy continent.
Something new under the water
Hints of the Antarctic Peninsula Coastal Current first showed up on
measurements taken by Robert Beardsley, an emeritus scientist at Woods
Hole Oceanographic Institution (WHOI) and Moffat’s co-advisor (with
WHOI physical oceanographer Breck Owens). Near Marguerite Bay,
Beardsley noticed a patch of unusually fresh water about 10.8 nautical miles (20 kilometers)
offshore, floating atop saltier, denser water.
In a stroke of serendipity, a biological survey led by WHOI biologist
Peter Wiebe had cut straight across the patch, Moffat learned. The
survey used BIOMAPER-II, an instrument that uses sonar to look for
marine animals while recording temperature, salinity,
and other basic data about the water. BIOMAPER measures continuously as
a ship drags it through the water—a vast improvement over previous
physical oceanography surveys in the area, which took measurements only
every 10.8 nautical miles (20 kilometers).
After some analysis with fellow graduate student (and BIOMAPER expert)
Gareth Lawson, Moffat found that the fresher water hit a wall of
saltier water offshore and deflected southward along the coast. Next,
Moffat calculated the current’s vital statistics using data from a
current sensor, deployed by Beardsley in 2001-2002, that had somehow
survived an entire winter in an ice-choked sea.
‘On’ in summer, ‘off’ in winter
Moffat found that the current rumbles southward at about 14 inches (35
centimeters)
per second (or not quite as fast as windshield
wipers move on the “slow” setting). The strongest part of the current
is 5.4 natuical miles (10 kilometers) wide and about 656 feet (200 meters) deep.
In all, Moffat
estimated, the current conveys about 0.32 Sverdrups of water each
year (a Sverdrup is 1 million cubic meters or 264 million U.S. gallons per
second). This is a trickle by ocean standards, but nearly twice the
volume of the
Amazon River. Most of that surge comes during the summer; Moffat found
that the current shuts down each winter when the coastal waters freeze
over.
The fresh water contained in the current’s yearly flow totals about 30 cubic miles (126
cubic kilometers)—enough to submerge all of Cape Cod under 394 feet or 120 meters of
water). Working with colleagues at the British Antarctic Survey and the Catholic University of Leuven, Belgium, Moffat
calculated that most of that fresh water arrives as meltwater from the
peninsula’s 1.75-mile (2,800-meter) -high mountains, kicking the coastal current
back into action as summer begins. As the water runs off the land, it
may bring nutrients that help recharge the growth of marine plants and animals in the coastal
waters, Moffat said.
In the larger picture, as Wiebe has suggested, the waters of the
new current may interject nutrients or juvenile krill from Marguerite
Bay into the much larger Antarctic Coastal Current, to feed waters
teeming with life as far away as South Georgia Island and the Weddell
Sea. (See “Voyages into the Antarctic Winter.”)
Science and cinema
Moffat, 30, grew up in and around Concepción, Chile, but traces his roots to
Scotland, which has both a town called Moffat and a gray-black-and-red
Moffat tartan. He met several WHOI scientists in 2001 when they
attended the inaugural Austral Summer Institute in Concepción, a
monthlong oceanographic symposium now in its seventh year.
The institute’s organizers had hired a promising undergraduate
assistant, remembers John Farrington, former dean of the MIT/WHOI Joint
Program. “And that was Carlos Moffat. We were all really impressed with
him. He was a biologist, but he had a strong mathematics background and
had already read some papers by Henry Stommel,” a WHOI physical
oceanographer who was a giant in the field.
“I encouraged him to apply for the Joint Program,” Farrington said, and
when Moffat came to WHOI later that year, as a Chilean Presidential
Fellow, Farrington welcomed him with a copy of Stommel’s collected
reprints.
By all accounts, Moffat’s English was exemplary from the start, but he
says he learned to speak less formally after watching American movies. His interest in U.S. cinema, which began back in Chile, eventually put him in charge of a weekly graduate student movie night
known for eclectic choices including How to Marry a Millionaire, Wicker
Man (the 1973 cult hit, not the 2006 flop), and Machuca, a 2004 film
about Chile in the turbulent 1970s.
Applying Seinfeld to climate change
Moffat reads voraciously. Back issues of Linux Journal litter his
living room and an empty Amazon.com box sits on his office desk,
perfect for putting his laptop screen at eye level. Despite a demanding
schedule—he defends his Ph.D. in 2007—he keeps a lively blog in Spanish
that rarely mentions oceanography. A recent post suggested it was about time Disney
let el ratón Mickey pass into the
public domain.
Just as Moffat turned to physical oceanography to help him understand
biology, he looks for science to bring solutions to the real world.
After studying the Antarctic Peninsula, one of the fastest-warming
places on the planet, he wishes more people took climate change
seriously.
For him, pop culture already has the right approach, at least when
viewed with his own wry wit. “Like when we got the news that Greenland
is melting: All these oil companies were getting really excited,
because now they can go there and look for oil,” he said. “It’s like
when Seinfeld went skydiving. Any time you get to the point where you
are buying a helmet, you should stop and think about what you are
doing. When it comes to climate change, it’s the same thing.”
— Hugh
Powell
Funding for this research came from
the Chilean Presidential Fellowship Program, the Coastal Ocean
Institute at WHOI, the Cooperative Institute for Climate and Ocean
Research at WHOI, and the National Science Foundation.
Posted: March 15, 2007 [top] |
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