Thursday, December 22, 2016

The Jet Stream At The Surface of Earth's Core

Very interesting:

Portion of caption: Figure 2: Northern polar view of the flow speed and direction at the CMB of the best-fitting high-latitude jet with M = 1 at epoch 2015. The line of 0° longitude is at the top of the figure and the tangent cylinder is marked as a thick white line. The large secular variation under Canada and Siberia can be explained by a cylindrical westwardly directed jet localized on t…

But now, scientists have used observations by the European Space Agency's Swarm satellites to identify another sort of jet stream, one that's made of molten metal instead of air and is located 1,865 miles beneath the Earth's surface, stretching from Siberia to Alaska.

The findings, contained in an article just published in the online edition of Nature Geoscience, depict a previously unknown geological feature that may yield secrets about the Earth's inner workings.

The jet stream inside the Earth is located along the border of two regions of the Earth's core, and it's about 261 miles in width. It moves about 25 miles in the course of a year. That's far slower than the hundreds of miles per hour at which the atmospheric jet streams travel, but three times faster than other parts of the outer core and hundreds of thousands of times faster than the Earth's tectonic plates. The interior jet stream gradually is accelerating, according to the scientists' findings.

"What's most surprising about the jet is that it's likely been in the core for many years and no-one has seen it before — not even with previous satellite missions," lead researcher Phil Livermore, an associate professor in the School of Earth and the Environment at the University of Leeds, said in an email. "The jet is likely to have been around in the core for some hundreds of millions of years, and we've only just glimpsed it through the technical-revolution of the Swarm mission."

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