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A Preliminary Risk Assessment of Geomagnetically Induced Currents over the Italian Territory

Papers from SWICo members

Roberta Tozzi, Paola De Michelis, Igino Coco, Fabio Giannattasio

A sketch representing the chain of events leading to the generation of GICs.

Major geomagnetic storms drive rapid intensification and variability of magnetospheric and ionospheric current systems that give rise to large ground geomagnetically-induced currents (GIC). Space weather associated GIC pose a serious threat to the reliability of power-transmission systems and other electrically conducting infrastructures such as oil and gas pipelines. The most severe effects are observed at high latitudes due to ionospheric currents associated with the aurora. However, as power transmission grid and pipeline infrastructures continue to grow at middle and low-latitudes, GIC hazards are no longer just concerns of high-latitude regions.

On the left: maximum daily GIC indices estimated from CTS geomagnetic data (blue line); thresholds between the different risk levels (coloured dashed lines); monthly averaged sunspot number (grey line). On the right: table of the threat and risk levels.

We provide a preliminary characterisation of the general risk to which the Italian power grid network is exposed. Due to limited direct GIC measurements, a proxy of the geoelectric field is used, i.e. the GIC index. This is calculated for a time interval of approximately 20 years using data from the two longest running Italian magnetic observatories, i.e. Castello Tesino and L’Aquila. Results show that during periods of high geomagnetic activity, potentially detrimental GICs could flow through the power network, especially at the highest Italian latitudes that are characterized by a low conductivity lithosphere.

Publication:  Tozzi, R., De Michelis, P., Coco, I., Giannattasio, F., 2019. A Preliminary Risk Assessment of Geomagnetically Induced Currents over the Italian Territory, Space Weather, 17, 46-58, doi: 10.1029/2018SW002065. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018SW002065

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