Energy channelled by space weather prefers the north: study

U of A physicists discover surprising new findings about how our planet’s magnetic field controls space weather as it shields us from solar wind

University of Alberta physicists have discovered a surprising imbalance in how the Earth responds to space weather driven by the sun. Energy generated as the electrically charged particles in solar wind hit the Earth result in more electromagnetic energy heading towards the magnetic north pole than to the magnetic south pole.

The sun bathes our planet in the light and heat to sustain life, but it also bombards us with dangerous charged particles in the solar wind. The resulting space weather has the potential to damage communication networks, navigation systems such as GPS and satellites. Severe solar storms can even cause electrical power outages, such as a 12-hour blackout that Quebec suffered in 1989.

Like a magnet, Earth’s magnetic field can be defined at the surface by the north and south magnetic poles that align loosely with the axis of rotation. Until now, it was assumed the same amount of electromagnetic energy in space would reach both hemispheres of our planet.

Using information from the European Space Agency’s (ESA) Swarm satellite constellation, the team of Canadian scientists led from the U of A discovered that electromagnetic energy transported by space weather clearly prefers the north. A key component of the research involved data from an electric field instrument developed in Canada by the University of Calgary. The research discovery resulted from a partnership between the two Alberta universities and ESA, and highlights international research excellence in space science in the province.

Ian Mann
Ian Mann

“We are fortunate that we have ESA’s three Swarm satellites in orbit, delivering key information that is not only vital for our scientific research, but can also lead to some very practical solutions for our daily lives,” said U of A co-author Ian Mann, professor in the Department of Physics.

“Because the south magnetic pole is farther away from Earth’s spin axis than the north magnetic pole, an asymmetry is imposed on how much energy makes its way down towards Earth in the north and south,” explained Ivan Pakhotin, lead author and post-doctoral fellow in the Department of Physics.

Ivan Pakhotin
Ivan Pakhotin

The new findings suggest that in addition to shielding Earth from incoming solar radiation, the magnetic field also actively controls how the energy is distributed and channelled into the upper atmosphere.

“We are not yet sure what the effects of this asymmetry might be, but it could also indicate a possible asymmetry in space weather and perhaps also between the aurora australis in the south and the aurora borealis in the north,” said Pakhotin. “Our findings also suggest that the dynamics of upper atmospheric chemistry may vary between the hemispheres, especially during times of strong geomagnetic activity.”

“The sun’s activity, such as mass coronal ejections, can have potentially serious consequences for our modern way of living,” said Mann. “So studying the underlying physics of space weather and the complexities of our magnetic field is very important for building up early warning systems and designing better electrical grids which are better able to withstand the disturbances the sun throws at us.”

In orbit since 2013, the three identical Swarm satellites have not only returned information about how Earth’s magnetic field protects us from the dangerous particles in solar wind, but also yielded insights into how the field is generated, how it varies and how the position of magnetic north changes over time.

The study, Northern preference for terrestrial electromagnetic energy input from space weather, was published in Nature Communications.

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