"Auroras and geomagnetically induced currents are caused by similar space weather drivers," explained Dr. Denny Oliveira of NASA's Goddard Space Flight Center, lead author of the article. "The aurora is a visual warning that indicates that electric currents in space can generate these geomagnetically induced currents on the ground."
"The auroral region can greatly expand during severe geomagnetic storms," he added. "Usually, its southernmost boundary is around latitudes of 70 degrees, but during extreme events, it can go down to 40 degrees or even further, which certainly occurred during the May 2024 storm-the most severe storm in the past two decades."
Understanding Auroras and Geomagnetically Induced Currents
Auroras are produced through two primary processes: particles from the sun interacting with Earth's magnetic field to create geomagnetic storms, or interplanetary shocks compressing the magnetic field. These same shocks can also generate geomagnetically induced currents that damage infrastructure. Both powerful and frequent, less intense shocks pose significant risks.
"Arguably, the most intense deleterious effects on power infrastructure occurred in March 1989 following a severe geomagnetic storm-the Hydro-Quebec system in Canada was shut down for nearly nine hours, leaving millions of people with no electricity," said Oliveira. "But weaker, more frequent events such as interplanetary shocks can pose threats to ground conductors over time. Our work shows that considerable geoelectric currents occur quite frequently after shocks, and they deserve attention."
Impact of Shock Angle on Currents
Research indicates that shocks hitting Earth head-on compress the magnetic field more effectively, inducing stronger currents. Scientists analyzed geomagnetically induced currents from a natural gas pipeline in Mantsala, Finland, cross-referencing these with data on interplanetary shocks. They categorized the shocks by angle and examined their effects.
They discovered that nearly frontal shocks produce higher current peaks both immediately and during subsequent substorms, particularly around magnetic midnight. This period also correlates with intense auroral activity.
"Moderate currents occur shortly after the perturbation impact when Mantsala is around dusk local time, whereas more intense currents occur around midnight local time," said Oliveira.
Forecasting and Protection
Predicting shock angles up to two hours in advance offers an opportunity to safeguard vulnerable infrastructure. Operators could manage specific electrical circuits to minimize the impact of geomagnetically induced currents.
"One thing power infrastructure operators could do to safeguard their equipment is to manage a few specific electric circuits when a shock alert is issued," suggested Oliveira. "This would prevent geomagnetically induced currents reducing the lifetime of the equipment."
However, the study noted a lack of strong correlation between shock angle and the time taken to induce a current, likely due to limited data. More widespread and accessible data from power companies worldwide would improve understanding and response strategies.
"Current data was collected only at a particular location, namely the Mantsala natural gas pipeline system," cautioned Oliveira. "Although Mantsala is at a critical location, it does not provide a worldwide picture. In addition, the Mantsala data is missing several days in the period investigated, which forced us to discard many events in our shock database. It would be nice to have worldwide power companies make their data accessible to scientists for studies."
Related Links
University of Maryland, Baltimore County
Solar Science News at SpaceDaily
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