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Scientists aglow after big discovery during tsunami

By Jim Borg

POSTED:
LAST UPDATED: 03:45 p.m. HST, Jul 16, 2011


Researchers using a camera on Maui have photographed the glow from atmospheric pressure disturbances generated by the March 11 tsunami, raising hopes that the technique could be used to predict the arrival of future waves.

The first observation of its kind was made from the Air Force Maui Optical and Supercomputing Station atop Haleakala by scientists in France, Brazil and the United States.

The March 11 earthquake in Japan generated a seismic sea wave that devastated parts of northern Honshu and caused millions of dollars of damage in Hawaii.

On the open ocean, such waves move at 500 mph but are only an inch high. Nevertheless, they put pressure on the atmosphere, scientists say.

"The atmosphere gets less and less dense as you get higher, and that allows the amplitude of the wave to grow," Jonathan Makela, a professor of electrical and computer engineering at the University of Illinois, Urbana-Champaign, said by phone Thursday.

At an altitude of 155 miles, the wave pressure interacts with the charged plasma of the ionosphere, which creates a faint red glow, Makela said.

"The light that we're looking at is red, but it is very, very dim," he said. "It's not something you could see with the naked eye."

On March 11, Makela awoke at home in Illinois to find emails from French collaborator Philippe Lognonne, who had heard about the quake. He asked Makela to recalibrate the camera, called the Cornell All-Sky Imager, to pick up the tsunami phenomenon, which had been predicted in the 1970s but never observed.

Makela did so and hit pay dirt in the pre-dawn darkness atop the 10,023-foot peak.

Their findings appear in the online edition of Geophysical Research Letters.

Makela and colleagues found that the first ionospheric "chemiluminescence" preceded the ocean wave by about an hour, leading them to propose a space-based system for tsunami early warning.

The Haleakala camera can detect such ionospheric glow only on clear moonless nights, but a similar camera in geosynchronous orbit could detect it day or night, Makela said.

Currently, scientists rely on ocean buoys and models to track and predict the path of a tsunami.

Makela's normal research at Haleakala is focused on how the ionosphere affects radio signals.

The tsunami findings were a "happy accident," he said.

"It shows the importance of having instruments out in the field taking data, because you never know what you're going to see," he said.

 






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