Research on auroras and induced geomagnetic currents reveals that the angle of interplanetary shocks against the Earth’s magnetic field critically affects the severity of the currents affecting electrical infrastructures. Direct strikes tend to cause stronger currents, which can lead to widespread power outages. Anticipating these shocks can help mitigate risks to critical infrastructure.
Scientists find that interplanetary shocks that strike Earth’s magnetic field cause more powerful electrical currents at ground level, threatening submarine pipelines and cables.
Auroras are caused by particles from the sun hitting the Earth’s magnetic field – but these impacts also cause induced geomagnetic currents at ground level, which can damage infrastructure that conducts electricity. Scientists who study these currents to protect critical infrastructure have conducted the first research comparing interplanetary shocks with real-time measurements of induced geomagnetic currents, showing that the angle of impact of shocks is key to predicting potential damage to infrastructure: shocks hitting magnetic fields at an angle produces less powerful currents.
Impact of interplanetary impacts on infrastructure
Auroras have inspired myths and omens for millennia—but only now, with modern technology dependent on electricity, are we appreciating their true power. The same forces that cause auroras also cause currents that can damage infrastructure that carries electricity, such as pipelines. Now scientists are writing in Frontiers in Astronomy and Space Sciences have demonstrated that the angle of impact of interplanetary shocks is key to the strength of currents, providing an opportunity to predict dangerous shocks and protect critical infrastructure.
“Auroras and geomagnetically induced currents are caused by similar space weather triggers,” explained Dr Denny Oliveira of NASA‘s Goddard Space Flight Center, lead author of the article. “The aurora is a visual warning that electric currents in space can generate these induced geomagnetic currents on Earth.”
“The auroral region can be greatly expanded during strong geomagnetic storms,” he added. “Normally, its southernmost limit is around 70 degrees latitude, but during extreme events it can drop to 40 degrees or even further, which certainly happened during the May 2024 storm – the most severe storm in two decades.” .”
Lights, Colors, Action
Auroras are caused by two processes: either particles ejected from the sun reach the Earth’s magnetic field and cause a geomagnetic storm, or interplanetary shocks suppress the Earth’s magnetic field. These shocks also generate induced geomagnetic currents, which can damage infrastructure that conducts electricity. Stronger interplanetary shocks mean more powerful currents and auroras – but frequent, less powerful shocks can cause damage.
“Arguably, the most intense damaging effects on power infrastructure occurred in March 1989 after a severe geomagnetic storm – the Hydro-Quebec system in Canada was shut down for nearly nine hours, leaving millions of people without electricity,” Oliveira said. “But weaker and more frequent events, such as interplanetary impacts, may pose a threat to ground-based transmitters over time. Our work shows that significant geoelectric currents occur quite often after shocks, and they deserve attention.”
Shocks that hit Earth head-on, rather than at an angle, are thought to cause stronger geomagnetic currents because they suppress the magnetic field more. Scientists investigated how induced geomagnetic currents are affected by shocks at different angles and times of day.
To do this, they took a database of interplanetary shocks and cross-referenced it with readings of geomagnetically induced currents from a natural gas pipeline in Mäntsälä, Finland, which is generally in the auroral region during active times. To calculate the properties of these shocks, such as angle and speed, they used data from the interplanetary magnetic field and the solar wind. The strokes were divided into three groups: high-prone strokes, medium-prone strokes, and near-frontal strokes.
Angle of attack
They found that more frontal shocks cause higher peaks in the induced geomagnetic currents both immediately after the shock and during the subsequent substorm. Particularly intense peaks developed around magnetic midnight, when the north pole would be between the sun and Mäntsälä. Localized thunderstorms at this time also cause a wonderful auroral glow.
“Moderate currents occur immediately after the impact of the disturbance when Mäntsälä is around dusk local time, while the most intense currents occur around midnight local time,” Oliveira said.
Because the angles of these shocks can be predicted up to two hours before impact, this information can allow us to put protections in place for power grids and other vulnerable infrastructure before stronger and stronger shocks hit.
“One thing power infrastructure operators can do to protect their equipment is to manage some specific electrical circuits when a shock alarm is issued,” Oliveira suggested. “This would prevent induced geomagnetic currents that would reduce the lifetime of the device.”
However, the scientists found no strong correlations between the angle of an impact and the time it takes for it to strike and then induce a current. This may be because more records of currents at different latitudes are needed to investigate this aspect.
“The actual data was only collected at one specific location, namely the Mäntsälä natural gas pipeline system,” Oliveira warned. “Although Mäntsälä is in a critical location, it does not offer a worldwide view. In addition, Mäntsälä’s records are missing several days in the investigated period, which forced us to discard many events in our companion database. It would be great if energy companies around the world made their data available to scientists for study.”
Reference: “First Direct Observations of Interplanetary Impact Angle Effects on Induced Geomagnetic Currents: The Case of the Finnish Natural Gas Pipeline System” by Denny M. Oliveira, Eftyhia Zesta, and Sergio Vidal-Luengo, May 7, 2024 Frontiers in Astronomy and Space Sciences.
DOI: 10.3389/fspas.2024.1392697