From Minnesota Public Radio : Robot divers to report on Lake Superior's depths
DULUTH, Minn. —
With its frigid, often ice-choked
water and legendary storms, Lake Superior can be a dangerous place for
scientists to conduct research.
"In Lake Superior, the season where
it's nice to go out there is relatively short," University of Minnesota
Duluth physics professor Jay Austin said. But he said "there's science
year round out there."
Aiming to tap the wealth of
information deep inside Lake Superior, Austin and other researchers are
preparing to send two mechanical divers in the big, cold lake for a long
time. They plan to test one of the divers Wednesday.
Funded by a $485,000 National
Science Foundation grant, the new devices, called "Autonomous Moored
Platforms," will travel up and down the depths on cables anchored to the
lake bottom. They'll collect readings on water temperature, currents
and a long list of other data points.
In the long run they could actually
save researchers money. A single day on a research vessel costs roughly
Austin, lead investigator on the new
project at the school's Large Lakes Observatory said the technology
will offer a view of Lake Superior science has never had before.
"We're very interested in being able
to have something where it's collecting a wide variety of data over the
course of the year," he said.
That's where the platforms come in.
The devices are big cylindrical tubes, about seven feet tall and contain
instruments that measure nitrates, light intensity, dissolved oxygen,
and a slew of other properties.
The cylinders, called profilers, are
made by WET Labs of Philomath, Ore. They sit on a platform moored to
the bottom of the lake.
At the click of a mouse button,
they'll travel up a cable towards the lake's surface, taking
measurements along the way. When they pop to the surface they'll
transmit the data back to the lab.
Austin said the profilers will help
eliminate a phenomenon known as "fair weather bias," because they can
operate below the water in any season.
"What this is doing is it's giving us a really continuous presence in the lake," he said.
By using the profilers, researchers
will be able to gather data under the ice in the depth of winter for the
first time, said Erik Brown, acting-director of the Large Lakes
Observatory at UMD.
"Making under-ice measurements is
complicated and dangerous, and it's just never been done," Brown said.
"Typically, people have just assumed during the winter, it's cold and
nasty and dark and nothing happens. That may not be the case. We don't
know what we don't know."
Brown said the devices also will
help monitor the effects of a changing climate. He cites the recent
record flooding that dumped tons of sediment into Lake Superior and
raised the water level by several inches.
"When we were writing the proposal,
if we would have said, 'we're going to look at big flood events,' people
would have said you're crazy," he said. "But it turns out this
instrumentation is really well-suited for looking at the effects of
events like the Duluth flooding."
Biologist Liz Minor, another
researcher on the project, said the system will also provide a much
clearer view of long-term trends.
"With sensors moving up and down in
the water at programmed times, we can get a nice long continuous record
of what's going on, which to us is very exciting," she said.
For the past several years the Large
Lakes Observatory has been tracking unprecedented changes in Lake
Total ice cover on the lake has
shrunk. Water temperatures are the highest they've been in a century.
But Austin stresses that the profilers aren't meant to measure the
influence of climate change on Lake Superior.
"We purchased them because there are
a lot of basic things about the ecosystem of the lake that were trying
to understand, and we're trying to establish a more robust presence in
the lake," he said.
Austin said the primary goal is to
know more about the lake and its processes. But he said eventually that
could inform practical applications such as expanding the Lake Superior