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For years, scientists studying the upper atmosphere assumed two measuring methods were the same. But were they?

By Diego Mendiola 
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Scientists have long assumed that two different methods for measuring the temperature of the Earth’s upper atmosphere are both quite accurate.

But researchers at Utah State University recently realized that there was no way to know for sure. That’s because the two remote sensing technologies — both of which use lasers to illuminate targets and analyze the reflected light that results — hadn’t been evaluated side-by-side.

Now having done so, the Utah State scientists will present their findings at the annual meeting of the American Geophysical Union, which will commence Monday in San Francisco.

Leda Sox, a Ph.D. student in Utah State’s physics department who participated in the study, said other scientists have combined data from Rayleigh Scattter Lidar — the technology that creates the recognizable “green beam” that shoots into the sky on many nights at the university’s Logan campus — and the fainter but more sensitive sodium lidar. But Sox said no one had collected the data from the same location, as Utah State’s scientists have now done.

Sox noted that the community of scientists that studies the upper atmosphere “is pretty small.” Long-held research assumptions that turn out to be incorrect could significantly damage the group’s collective body of work.

“It was kind of scary when we started this thing,” said Titus Yuan, an assistant research professor at Utah State. Both lidars are “measuring temperature in the same region, but are they giving a different result? That’s the most important question.”

It turns out that, on most nights, the two measurements are very similar — a research finding that came as a big relief, Yuan said.

– mdl