Abstract
The aim of the present contribution is to investigate the timing relations between enhancements in the Polar Cap (PC) indices and power grid disturbances related to geomagnetically induced currents (GIC). The polar cap indices, PCN (North) and PCS (South), are based on measurements of geomagnetic variations in the central polar caps. These variations are strongly related to the transpolar convection of plasma and magnetic fields driven by the solar wind. During cases of enhanced merging processes at the front of the magnetosphere and subsequent tailward convection of plasma and embedded magnetic fields, the magnetospheric tail configuration may accumulate excess energy, which upon release may cause violent substorm activity. Earlier reports have disclosed remarkably lengthy intervals, ranging up to several hours, of elevated PC index values preceding GIC-related power grid disruptions. The present investigation has shown that the delays of typically 3–4 h between increases in the PC indices and GIC-related power grid disturbances are related to displacements of the substorm processes responsible for strong GIC events to subauroral latitudes where vulnerable power grids reside. The results have shown that PC index values remaining above an “alert level” of 10 mV/m through more than 1 h indicate a high risk for violent GIC events that may threaten power grids and other vulnerable technical systems. These results support the application of real-time PC indices in space weather monitoring and forecast services.
Highlights
Geomagnetic variations related to auroral substorm activity may generate Geomagnetically Induced Currents (GIC) in conductive structures
The results have shown that Polar Cap (PC) index values remaining above an “alert level” of 10 mV/m through more than 1 h indicate a high risk for violent GIC events that may threaten power grids and other vulnerable technical systems
Enhanced merging at the front of the magnetosphere would in the first step lead to enhanced transpolar convection of plasma with embedded magnetic fields over the polar caps into the tail region
Summary
Geomagnetic variations related to auroral substorm activity may generate Geomagnetically Induced Currents (GIC) in conductive structures. At the magnetic observatories in Qaanaaq (Thule) in Greenland and Vostok in Antarctica in the central northern and southern polar caps, respectively (Troshichev et al, 1988, 2006) These magnetic variations are strongly related to the transpolar convection of magnetic fields and plasma driven by electric fields induced by the encounter of the solar wind and embedded Interplanetary Magnetic Field (IMF) with the Earth’s magnetosphere. The potential application of PC indices to forecast GIC-related power grid failures is discussed in Section 6 while the more general association of enhanced PC index levels with strong and rapid variations in the geomagnetic field is considered in Sections 7 and 8 followed by a summary in Section 9 and conclusions. The calculations performed here are based on the QDC derivation defined in Stauning (2011) and not on the methods described in Janzhura & Troshichev (2011) since their presentation is affected by grave errors (Stauning, 2013a, 2018a)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
