Intense, Long‐Duration Geomagnetically Induced Currents (GICs) Caused by Intense Substorm Clusters. Issue 3 (18th March 2022)

• Record Type: Journal Article
• Authors: Hajra, Rajkumar
• Is Part Of: Space weather. Volume 20:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-18
• Subjects: GIC -- space weather -- substorm; Space environment -- Periodicals; 551.509992
• DOI: 10.1029/2021SW002937
• Languages: English
• ISSNs: 1542-7390

Abstract

Abstract: Geomagnetically induced current (GIC) measurements at the Mäntsälä, Finland (57.9° magnetic latitude) gas pipeline from 1999 through 2019 are analyzed. It is found that the GIC events with peak intensity > 10 $ > 10$ A are not individual peaks, but occur in clusters with duration from ∼5 to ∼38 hr when GIC values are almost continuously above ∼1.5 A. The intense, long‐duration GIC > 10 $ > 10$ A clusters (ILG10 ) are characterized by average (median) duration of ∼17 ± 9 hr (∼14 hr), peak intensity of ∼21 ± 10 A (∼19 A), and time‐integrated current flows of ∼1.0 ± 0.7 A‐d (∼0.9 A‐d) for all events under study. An one‐to‐one correlation is observed between the ILG10 events and intense substorm clusters characterized by average (median) duration of ∼20 ± 10 hr (∼17 hr), peak westward auroral electrojet intensity (presented by SuperMAG AL or SML index) of ∼− 2, 238 ± 843 nT (∼− 2, 099 nT) for all events. About 10–60 min fluctuations in the ILG10 events are found to be induced by substorm (SML) activity, and geomagnetic pulsations. A detailed study is presented on the local time, solar cycle, and geomagnetic dependencies of the ILG10 events. This will hopefully augment the predictability of the intense GICs. Plain Language Summary: Geomagnetically induced currents (GICs) are intense, low‐frequency currents that flow through the gas pipelines and other long conductors. They result from the rapid changes in the geomagnetic fields induced by space weather events. In this work, a long database of GICs from a subauroral region is analyzed, and it is found that the strong GIC events with peak intensity > 10 $ > 10$ A are long‐duration events. In addition, long‐duration clusters of intense substorms are responsible for such events. The results will be hopefully useful for prediction of the strong GIC events, which is important for fail‐safe operation of the gas pipelines and other long ground‐based conducting systems. Key Points: Geomagnetically induced currents > 10 $ > 10$ A occur as long‐duration clusters Intense substorm clusters are most effective in causing such events Statistical relationship between the two are investigated