[StBernard] Lightning inside hurricane could predict intensity

[Westley Annis]

Lightning inside hurricane could predict intensity 
By SUE MAJOR HOLMES 
Associated Press Writer
LOS ALAMOS, N.M. - They're deceptively simple-looking detectors: one an
antenna with built-in GPS, the other electronic sensors inside a large,
upside-down metal salad bowl.

The sensors are the basis of a Los Alamos National Laboratory project
studying lightning inside a hurricane to improve the accuracy and timeliness
of forecasts for people in a storm's path.

The effort is in the second of three years of research. The team is gearing
up for the Atlantic hurricane season that peaks in August and September.

Hurricane watchers use satellite images and computer simulations to forecast
a storm's trajectory, but it's a challenge to predict how a hurricane will
strengthen or weaken as it approaches land, lightning and radio scientist
Xuan-Min Shao said.

Predictions of where a hurricane will hit have improved by 50 percent in the
past two decades, said Robert Atlas, director of the National Oceanic and
Atmospheric Administration's Atlantic Oceanographic and Meteorological
Laboratory near Miami.

But, he said, NOAA and its partners have not made the same leap in
forecasting storm strength, "largely because you're dealing with ... what's
going on within the hurricane itself."

After research, the next step would be an operational system. Los Alamos, as
a federal research laboratory, is not in the business of producing
forecasts.

"The National Weather Service does that," said Chris Jeffery, one of the
project's scientists. "This is a research and development project to
demonstrate new technology, understand new fundamental relationships."

Their project spun off from the lab's work in nuclear nonproliferation.

Scientists trying to ensure that countries are not secretly detonating
nuclear weapons must know the difference between radio signals produced by a
nuclear bomb and anything else - lightning, for example.

Lightning and nuclear bombs both release radio waves at different
frequencies.

The team, which has not published its research, found a close correlation
between lightning and hurricane intensification in a study of
nonproliferation sensor data gathered in 2005 during Hurricanes Katrina and
Rita.

"If your hurricane people see the lightning all of a sudden become very
active, you are probably expecting in the next couple hours that this
hurricane will be intensified," Shao said.

Finding lightning associated with a hurricane eyewall - the wall surrounding
the eye of the storm - is not new. But the Los Alamos scientists said their
data was gathered from greater distances and tracked not only lightning
bolts hitting the ground, but also flashes within clouds.

The intensity of intercloud flashes can help determine such things as the
height of the storm, which researchers said can help determine whether the
eyewall is symmetrical and tight.

The structure is important because a towering eyewall puts a lot of energy
into the storm, Jeffery said.

"Eventually that energy works its way up and if your conditions are right,
it forms a symmetric tight eyewall. It will spin up the storm," he said.

Jeffery is the principal investigator in the Hurricane Lightning Project,
which involves densely packing sensors around the New Orleans area to
observe hurricanes at a far higher resolution than possible in the past.

Scientist Cheng Ho heads a related project, the Los Alamos Sferic Array,
which has stations in Florida and along the Texas coast operating at a
low-frequency band that can detect storms thousands of miles away. The two
complementary arrays cover the entire U.S. Gulf Coast.

"So if we're lucky we'll get a reasonable size, but not very damaging,
hurricane hitting the New Orleans area, so we get the data but not much
damage," Ho said. "If somehow the hurricane goes the other direction, then
this wider arm will catch it."

Shao said the dual-band observations will not only pinpoint the location of
lightning for researchers but also the physics involved by producing a
three-dimensional picture.

The project needs multiple sensors to get a reading on the electromagnetic
pulse produced by lightning.

"We can compare all the signals from the different stations and triangulate
where the signal comes from," Shao said.

All the data gathered during a hurricane is sent over the Internet to Los
Alamos for the team to analyze. The GPS provides accurate time information
from the electromagnetic signals.

Pointing to a shelf with a line of retired sensors in inverted salad bowls
from the local supermarket, Shao joked, "These are Mach zero salad bowls and
we are going to Mach 4 salad bowls."

Atlas said new insights eventually could translate into improved forecasts
up to one week before a hurricane hits land - crucial because of the time
needed to evacuate a growing population along the coast.

"We believe if we do this, public confidence in the forecasts and public
adherence to warnings will be dramatically increased so lives will be
saved," he said.


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