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February 6, 2007
SATELLITES
AND
SEA LIONS: WORKING TOGETHER TO IMPROVE OCEAN MODELS
The best
oceanographers in the world never studied at a university. Yet they
know how to
navigate expertly along oceanic fronts, the invisible boundaries
between waters
of different temperatures and densities. These ocean experts can find
rich
fishing in places and at depths that others would assume are barren.
They
regularly visit the most interesting and dynamic parts of the sea.
Sea lions, seals, sharks, tuna and other top ocean predators share some
of
their experiences with human researchers, thanks to electronic tags.
Besides
tracking the animals, these sensors also collect oceanographic data,
such as
temperature and salinity. Scientists are beginning to incorporate this
rich
store of information into ocean models providing new insights into the
inner
workings of the ocean and the lives of its creatures.
"Our goal is to produce a three-dimensional model of the ocean," says
JPL oceanographer Dr. Yi Chao. Chao uses data from satellites, ships,
buoys and
floats to map the currents, heat content and different water densities
beneath
the ocean surface. When Chao heard Dr. Dan Costa, a professor of marine
biology
at the University
of California,
Santa
Cruz, present some of his animal
tagging data at a
scientific meeting a few years ago, he saw an opportunity to improve
his ocean
models. Costa recognized a chance to get a clearer picture of the place
where
his research subjects live.
Chao and Costa started their collaboration with sea lions. Costa
studies how
marine mammals adapt to the ocean environment. As part of his research,
he and
his students tag and track California
sea
lions off the coast of Santa Cruz.
Chao and his colleagues at JPL used the independent temperature data
collected
by the sea lions to see how well their ocean model could predict the
temperature at specific depths. Then they worked on ways of
assimilating the
sea lion data with more conventional oceanographic data to create more
accurate
and detailed ocean models. "Satellites provide a two-dimensional view
of
the ocean," says Chao. "Animals give us a slice of the ocean. They're
like weather balloons in reverse."
The research collaboration now includes Dr. Barbara Block, a professor
of
marine sciences at Stanford
University,
Palo
Alto, Calif.,
and the
scientists have added tagging data collected from tuna and sharks to
their
studies. Together with a group called TOPP, for Tagging of Pacific
Pelagics,
they are now working to expand the use of environmental and biological
data
collected by ocean inhabitants.
"We are at the forefront of knowing how animals use the ocean," says
Costa. "But we want to understand the environment better. We still see
the
ocean primarily as deep or shallow or near-shore or offshore. But just
as there
are different habitats on land, the ocean has fine-scale features that
are very
important to animals," he explains. "We want to be able to look at
the ocean and say the equivalent of "this is a grassland" or "this
is a forest."
In late January, Costa and his research group headed up the California
coast to begin tagging elephant
seals and collecting tags that were deployed last spring. The work is
strictly
regulated to ensure that the animals are protected from harm, and it
requires a
permit from the National Marine Fisheries Service.
"We're constantly learning new things about these animals that are
amazing," Costa says. One of his students recently tagged a 17-year old
female elephant seal and discovered that the animal had been tagged
before,
when she was 6. "She went to the same place that she did 11 years
ago," says Costa. "What clues is she using to be able to follow the
same track? Better ocean models can tell us what's out there, what
currents she
faced and what the habitats are like."
"Marine scientists have been tracking marine animals for years," says
Chao. "It's an interesting challenge, though, to use the data. There
are
all sorts-- from tuna, sharks, seals--you name it. Some of these data
sets have
small errors, others much larger errors. Figuring out how to put these
in our
system is a challenge, "he says. "But five years from now, we should
be able to see the ocean the way a turtle sees it."
"As we are getting more data from the sea and improving our computer
models,"
says Chao, "we should be able to make routine ocean forecasts, similar
to
what meteorologists have been doing in the past few decades. People who
open
the newspaper or turn on the TV in the morning will see the updated
ocean
forecast and make appropriate decisions as they plan their activities
on the
sea."
What is most important about using marine animals as ocean sensors is
that the
work benefits the animals, Costa explains. "Collaborations between
biologists like Barbara Block and me and physical oceanographers like
Yi are
critical for understanding why the animals go where they go," he says,
"as we need to know and understand the ocean physics and its
relationship
to climate processes. Further, the ability to understand how climate
change is
affecting the world oceans is not only of benefit to humans, but is
vital for
trying figure out what is going to happen to habitat of marine animals."
For more information and
images,
visit:
http://www.jpl.nasa.gov/news/features.cfm?feature=1283
http://www.nasa.gov/vision/earth/lookingatearth/sealion-20070206.html
##
Contact:
Alan Buis
NASA Jet Propulsion Laboratory
818-354-0474
alan.d.buis@jpl.nasa.gov
This text is
derived from:
http://www.jpl.nasa.gov/news/features.cfm?feature=1283
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