According to new research, not all solar storms can be detected by systems currently in use. Described in the Journal of Space Weather and Space Climate, this possible detection failure poses a significant threat to the world power supply and communication network.

Solar storms, also known as geomagnetic storms, are temporary disturbances of the Earth’s magnetosphere caused by intense solar activity. The most powerful solar storm on record, the Carrington event, was responsible for aurorae from the poles to the tropics as well as generating fires in telegraph stations across the U.S. and Europe in 1859. It was estimated that the cost of a solar storm of such magnitude today could be in the order of trillions of dollars for the U.S. alone.

The most widely used index for measuring a geomagnetic storm is the Dst (Disturbance storm time), which is obtained by averaging data from four observatories around the world: Hermanus (South Africa), Kakioka (Japan), Honolulu (Hawaii, USA) and San Juan (Puerto Rico). The index is updated every hour. A more precise index, SYM-H, collects data from even more observatories, with readings obtained every minute. Both indices assess the magnetic field at a specific latitude.

One of the largest solar storms in recent years was the Halloween Solar Storm, which took place between October and November 2003. The storm caused fires at power stations in South Africa and an hour-long blackout in Sweden. The event was detected, but only by the Tihany Magnetic Observatory in Hungary. The team behind this latest research from the University of Alcalá has now analyzed why it wasn’t detected by the official indices and the consequences of it.

“One of the conclusions is that the indices commonly used by scientists – such as Dst or SYM-H, which are based on an overall perspective of the Earth and obtained by calculating averages – failed to detect such an important event, and they most likely would have failed to detect the Carrington Event as well,” explained Professor Consuelo Cid, the lead author, in a statement.

The study claims that by using worldwide averages, the positive and negative magnetic disturbances in local observatories might cancel each other out, leading to a failure in detection, like in the case of the Halloween Solar Storm.

The team has developed a new index based on local magnetic readings, which depends on both latitude and longitude. The Local Disturbance Index for Spain calculates the geomagnetic perturbation over the Iberian Peninsula by using the San Pablo Observatory in Toledo. They argued that similar indices should be developed in other areas of the world and that researchers should collaborate with the companies, such as electricity providers, that might be affected most severely by solar storms.


  1. […] Such an event would easily overwhelm what a single nation can cope with and the team stressed the importance of strengthening the link already in place between the US and Europe for predicting potential storms. There’s still a lot we don’t know about the Sun and being able to forecast space weather is one of those knowledge gaps we need to fill. We might miss the big one otherwise. […]


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