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Swarm detects asymmetry

22 March 2017

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Strong electric currents in the upper atmosphere are known to vary according to the season, but ESA's Swarm mission has discovered that this seasonal variation is not the same in the north and south polar regions.

Named after Kristian Birkeland, the scientist a century ago who first postulated that the 'northern lights' were linked to electrically charged particles in the solar wind, these currents flow along Earth's magnetic field lines in the polar regions.

Magnetic field measurements from ESA's Swarm satellite constellation are allowing scientists to understand more about these powerful currents, which carry up to 1 TW of electric power to the upper atmosphere. This is about 30 times the energy consumed in New York during a heatwave.

It is important to understand the interplay between these Birkeland currents and the solar wind that bombards our planet and that can potentially cause power and communication blackouts.

New findings, presented this week at the Swarm science meeting in Canada, show how three years of measurements from the mission were combined with measurements from Germany's earlier Champ satellite to produce global climatological maps of these currents.

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