Equatorial Regions Prone To Disruptive Space Weather

Smaller scale space weather events are amplified near the equator, putting power grids at risk in regions previously considered safe, a new study finds. Extreme space weather events have deep-sixed power grids across North America and Europe, however, the new report cautions that smaller events strike, often with little warning, in equatorial regions with higher frequency than previously known, says Brett A. Carter, lead author of the report and a visiting scholar at Boston College’s Institute for Scientific Research.

Carter, a space physicist who is also affiliated with RMIT’s SPACE Research Centre in Melbourne, Australia, said:

“These disturbances affect what’s happening in the equatorial region, which has largely been overlooked. What the historical data also show is that we don’t need huge geomagnetic storms to experience the effects. They can also take place during what we might otherwise classify as ‘quiet’ periods of space weather.”

To put it another way, electrical disruptions in the equatorial region do not need severe geomagnetic storms, similar in scale to events that have crashed power grids in the past, most notably in Quebec in 1989 and in Sweden in 2003.

Carter and his team invesigated the effects of interplanetary shocks in the solar wind, which is the stream of charged particles that flows out of the Sun. Massive explosions on the Sun’s surface can cause these shocks, but many are created through far less violent means.

The arrival of these shocks at Earth causes complex phenomena in the Earth’s magnetosphere and ionosphere, which provokes spikes in current at the Earth’s surface, said Carter.

“The Earth’s magnetic field does the job of shielding the Earth from the solar wind and when it gets hit by these shocks, you get a global magnetic signature at the ground,” Carter said. “This magnetic signature becomes locally amplified by rapid changes in the equatorial electrojet, which increases the induced current levels in the ground near the equator.”

These are not “doomsday” scenarios like those posed by extreme space weather events. But these smaller episodes can damage unprotected power infrastructure and even cause fluctuations in wholesale electricity pricing, as surges in induced current at the Earth’s surface effectively confuse systems monitoring rates of supply and demand.

The findings should prompt scientists to examine the implications on regional infrastructure and economies near the equator.

The study was published online in Geophysical Research Letters

Illustration: The equatorial electrojet is a naturally occurring flow of current approximately 100 kilometers (60 miles) above the Earth’s surface. Credit: Brett A. Carter