The Interplanetary and Magnetospheric causes of Geomagnetically Induced Currents (GICs) > 10 A in the Mäntsälä Finland Pipeline: 1999 through 2019

The interplanetary and magnetospheric phenomena time-coincident with intense geomagnetically induced current (GIC) > 10 A 30 events during 21 years (1999 through 2019) at the Mäntsälä, Finland (57.9° magnetic latitude) gas pipeline have been studied. Although forward shocks substorms are predominant causes of GICs, some newly discovered geoeffective features are: solar wind plasma parcel (PP) impingements, possible field (IMF) northward (Bn) southward (Bs) turnings, reverse shocks. PPs possibly loop filament portions coronal mass ejections (CMEs). From a study GIC events, it is found that supersubstorm ( SSS : SML < −2500 nT) substorm (−2500 nT −2000 auroral electrojet intensifications most frequent (76%) cause all these events. These occur often in superstorm SYM-H ≤ −250 main phases, but they can other storm phases lesser intensity storms as well. After substorms, were Mäntsälä Forward third Shock-related GICs observed to local times. two “Halloween” superstorms 29–30 30–31 October 2003 produced by far greatest number interval (9 168 GICs). In first Halloween superstorm, shock-triggered −3548 caused 33, 57, 51 52 GICs. 57 was event this study. It new form substorm. Equally also studied their related less numerous intense.