On the left is and aurora oval before the auroral breakup occurs On the right is a supercomputer simulation reveals how auroral breakups develop Hot charged particles, or plasmas, gather in near-Earth space – just above the upper atmosphere of the polar region – when magnetic field lines reconnect in space. This makes the plasma rotate, creating a sudden electrical current above the polar regions. Furthermore, an electric current overflows near the bright aurora in the upper atmosphere, making the plasma rotate and discharge the extra electricity. This gives rise to the ‘surge’, the very bright sparks of light that characterize substorms. Credit: Kyoto University
A supercomputer model revealed the rotation of plasma creates electrical currents in the near-Earth space, ultimately triggering auroral breakups. This overthrows existing theories about how auroral breakups occur. Auroras are dimly present throughout the night in polar regions, but sometimes these lights explode in brightness. For years, scientists have contemplated what triggers the formation of auroral substorms and sudden bursts of brightness.
The Kyoto-Kyushu research team has revealed that hot charged particles, or plasmas, gather in near-Earth space – just above the upper atmosphere of the polar region – when magnetic field lines reconnect in space. This makes the plasma rotate, creating a sudden electrical current above the polar regions. An electric current overflows near the bright aurora in the upper atmosphere, making the plasma rotate and discharge the extra electricity >> gives rise to the “surge,” ie very bright sparks of light of substorms. “This isn’t like anything that us space physicists had in mind,” said Yusuke Ebihara of Kyoto University. Ebihara based the study on a supercomputer simulation program developed by Takashi Tanaka, professor emeritus at Kyushu University.
Auroras originate from plasma from the sun, known as the solar wind. In the 1970s, scientists discovered that when this plasma approaches the Earth together with magnetic fields, it triggers a change in the Earth’s magnetic field lines on the dayside, and then on the night side. This information alone couldn’t explain how the fluttering lights emerge in the sky, however.
The current paper builds on earlier work by Ebihara and Tanaka about how the bursts emerge. This explores the succeeding processes, namely how the process expands into a large scale breakup. The research also has the potential to alleviate hazardous problems associated with auroral breakups that can seriously disrupt satellites and power grids.
http://www.eurekalert.org/pub_releases/2015-12/ku-ams121415.php
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