Beyond Auroras: How Geomagnetic Storms Threaten Our Power and Communication Systems

Aurora borealis
Ksenija Brakočević
Ksenija Brakočević
7 min

Geomagnetic storms are disturbances of the Earth's magnetosphere caused by solar wind shock waves. We are the most familiar with them through the visual phenomenon of auroras but these storms can cause severe disturbances in power networks as well as disturb radio, communication, and navigation systems. Health hazards of geomagnetic storms are still being speculated and studied, but the effect of these events on life on Earth is more than evident. In this article, our aim is to explain this phenomenon as well as describe related consequences, especially regarding the power systems.

As previously mentioned, geomagnetic storms are caused by solar winds, more precisely they can be caused by solar coronal mass ejection, or a high-speed solar wind originating from a coronal hole. Geomagnetic storms are affected by the sunspot cycle, which means that during the solar maxima, they occur more often. It took some time for scientists to discover relationship between sunspot cycles and geomagnetic storms, which was a ground-breaking finding for further research of this phenomena.

Solar wind causes increased pressure on Earth magnetosphere, which causes interactions between two magnetic fields, their deformity, and increased plasma movement inside magnetosphere which creates electrical field and electrical currents that can cause damage to both space equipment and power grids.

Parameter that is primarily observed concerning the geomagnetic storms is DST – disturbance storm time. DST index estimates globally average change of the horizontal component of the magnetic field at the magnetic equator. Normal values of DST are from -20 to 20 nT. Initial phase of the geomagnetic storm has values of from 20 to 50 nT, main phase from -50 to -600 nT, whereas recovery phase has DST values from the main phase minimal to the normal values. The main phase typically lasts about 8 hours, while the recovery phase lasts from 8 hours up to a week.

Intensity-based classification of geomagnetic storms is important because it is related to the magnitude of the consequences of the event. Moderate geomagnetic storms have intensity of −50 nT > minimum of DST > −100 nT, intense −100 nT > minimum DST > −250 nT, super storm minimum of DST < −250 nT. There are estimations that the minimal DST value can be up to -2500 nT, even though a value even remotely close to this has never been detected. The most severe geomagnetic storm ever recorded occurred in 1859, destroying the newly established telegraphic network, starting fires, and causing severe damage. Another severe storm happened in 1989 when ground-induced currents caused disruptions in power network throughout entire Quebec region. It is estimated that if the event of 1859 happened now, it would cause loss of billions of dollars, blackouts which would take a while to restore, possible issues of food production and supply, and many others.

Geomagnetic storms cause issues for power systems most notably in the following way: moving magnetic field in proximity to the conductor causes induced current, during geomagnetic storms this process occurs on the grand scale, thus causing induced currents which long transmission lines are especially susceptible to. These currents are not only damaging to the transmission lines but also to the transformers whose cores and coils can overheat and transformer can be permanently damaged. In general, it is estimated that the generators themselves would not suffer damage due to geomagnetic storm, because they are heavily protected by relays, and their block transformers would be the one to take the bulk of the damage. Consequences for the equipment are highly dependent on previous conditions in the grid. Another danger of geomagnetically induced current is the tripping of protection devices, which can also cause and spread blackout.

It is important to note that the damage caused by geomagnetic storms is not only focused on power systems but also the internet, radio, communication, spacecraft, navigation systems, etc. Mechanism is mostly similar to the previously mentioned, but in general magnetic field as well as electrical field and currents that consequentially appear, cause disturbances of mentioned systems and devices, while it needs to be mentioned that some are more sensitive than others.

Health hazards of geomagnetic storms need to be further researched, but at this point, it is safe to say that due to disturbances in the magnetosphere, protection from the Sun’s radiation in case of geomagnetic storms weakens, which especially affects astronauts, pilots, and aircrew. These disturbances can allow high-energy solar protons to pass through protective layers of the Earth and cause radiation poisoning. An increased number of neutrons post geomagnetic storm, greatly affects the rise of the cancer risk.

Animals with magnetoreceptors are severely endangered by these events. It has been suggested that whales beach themselves due to this disturbance. It is very likely that animals are affected by geomagnetic storms in many other ways, but this area needs further observations and research.

The aim of this article was to show aspects of geomagnetic storms beyond beautiful and colourful auroras, their cause, mechanism, and consequences. We hope that we managed to inspire you to dive in into further research of this topic, which is as fascinating as auroras are beautiful.

References

  • Gonzalez, W. D., Joselyn, J. A., Kamide, Y., Kroehl, H. W., Rostoker, G., Tsurutani, B. T., & Vasyliunas, V. M. (1994). What is a geomagnetic storm? Journal of Geophysical Research, 99(A4), 5771. doi:10.1029/93ja02867
  • Lakhina, G. S., Tsurutani, B. T., (2016). Geomagnetic storms: historical perspective to modern view. DOI 10.1186/s40562-016-0037-4
  • National Academies of Sciences, Engineering, and Medicine. 2008. Severe Space Weather Events: Understanding Societal and Economic Impacts: A Workshop Report. Washington, DC: The National Academies Press. https://doi.org/10.17226/12507.
  • National archives. Federal Register: The Daily Journal of the United States Government. Reliability Standard for Transmission System Planned Performance for Geomagnetic Disturbance Events (2016)