If it does not predict the
dispersion of the pollutants it will certainly point to break points that will
naturally retro adjust the modeling to improve its predictive powers. One still has to map flow patterns and we are
some ways away from having that information.
Yet with this technique in hand
we now have the justification to develop measuring devices that capture that
information which would have otherwise been meaningless. Thus flow patterns are predictable and like
the weather which is also about flow patterns, there is a clear economic
incentive to gather the data. In fact
the weather department needs to be able to also spot pollutants as they are the
guys with tools and boots on the ground.
We are needing resolution that
the weather boys only dream about but the fact remains that they need the
resolution also and technology is today able to deliver that resolution.
The shape of things to come
by Staff Writers
Using Lagrangian Coherent Structures scientists at the Univeristy of
Miami and McGill University were able to study the internal movements of oil in
the Gulf of Mexico, and can use this same methodology in the study of volcanic
ash, according to a study published in Proceedings from the National Academy of
Sciences. Credit: UM/RSMAS.
When oil started gushing into the Gulf of Mexico
in late April 2010, friends asked George Haller whether he was tracking its
movement. That's because the McGill engineering professor has been working for
years on ways to better understand patterns in the seemingly chaotic motion of
oceans and air. Meanwhile, colleagues of Josefina Olascoaga in Miami were asking the geophysicist a similar
question. Fortunately, she was.
For those involved in managing the fallout from environmental
disasters like the Deepwater Horizon oil spill, it is essential to have tools
that predict how the oil will move, so that they make the best possible use of
resources to control the spill.
Thanks to work done
by Haller and Olascoaga, such tools now appear to be within reach. Olascoaga's
computational techniques and Haller's theory for predicting the movement of oil
in water are equally applicable to the spread of ash in the air, following a
volcanic explosion.
"In complex systems such
as oceans and the atmosphere, there are a lot of features that we can't
understand offhand," Haller explains. "People used to attribute these
to randomness or chaos. But it turns out, when you look at data sets, you
can find hidden patterns in the way that the air and water move."
Over the past decade, the team has developed mathematical methods to
describe these hidden structures that are now broadly called Lagrangian
Coherent Structures (LCSs), after the French mathematician Joseph-Louis
Lagrange.
"Everyone knows about the Gulf Stream, and about the winds that
blow from the West to the East in Canada ," says Haller,
"but within these larger movements of air or water, there are intriguing
local patterns that guide individual particle motion." Olascoaga adds,
"Though invisible, if you can imagine standing in a lake or ocean with one
foot in warm water and the other in the colder water right beside it, then you
have experienced an LCS running somewhere between your feet."
"Ocean flow is like a busy city with a network of roads,"
Haller says, "except that roads in the ocean are invisible, in motion, and
transient." The method Haller and Olascoaga have developed allows them to
detect the cores of
LCSs. In the complex network of ocean flows, these are the equivalent of
"traffic intersections" and they are crucial to understanding how the
oil in a spill will move.
These intersections unite incoming flow from opposite directions and
eject the resulting mass of water. When such an LCS core emerges and builds
momentum inside the spill, we know that oil is bound to seep out within the
next four to six days. This means that the researchers are now able to
forecast dramatic changes in pollution patterns that have previously been
considered unpredictable.
So, although Haller wasn't tracking the spread of oil during the
Deepwater Horizon disaster, he and Olascoaga were able to join forces to
develop a method that does not simply track: it actually forecasts major
changes in the way that oil spills will move. The two researchers are confident
that this new mathematical method will help those engaged in trying to control
pollution make well-informed decisions about what to do.
The research was
funded by: the U.S. National Science Foundation (NSF), NIH/National Institute
of Environmental Health Sciences, NASA, BP/The Gulf of Mexico Research
Initiative, and Natural Sciences and Engineering Research Council of Canada (NSERC).
The University of Miami is the largest private research institution in
the southeastern United
States . The University's mission is to
provide quality education, attract and retain outstanding students, support the
faculty and their research, and build an endowment for University initiatives.
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