Geomagnetic Disturbances That Cause GICs: Investigating Their Interhemispheric Conjugacy and Control by IMF Orientation

Mark J. Engebretson, Laura E. Simms, Viacheslav A. Pilipenko, Lilia Bouayed, Mark B. Moldwin, James M. Weygand, Michael D. Hartinger, Zhonghua Xu, C. Robert Clauer, Shane Coyle, Anna N. Willer, Mervyn P. Freeman, Andy J. Gerrard

Research output: Contribution to journalArticlepeer-review

Abstract

Nearly all studies of impulsive geomagnetic disturbances (GMDs, also known as magnetic perturbation events MPEs) that can produce dangerous geomagnetically induced currents (GICs) have used data from the northern hemisphere. In this study, we investigated GMD occurrences during the first 6 months of 2016 at four magnetically conjugate high latitude station pairs using data from the Greenland West Coast magnetometer chain and from Antarctic stations in the conjugate AAL-PIP magnetometer chain. Events for statistical analysis and four case studies were selected from Greenland/AAL-PIP data by detecting the presence of >6 nT/s derivatives of any component of the magnetic field at any of the station pairs. For case studies, these chains were supplemented by data from the BAS-LPM chain in Antarctica as well as Pangnirtung and South Pole in order to extend longitudinal coverage to the west. Amplitude comparisons between hemispheres showed (a) a seasonal dependence (larger in the winter hemisphere), and (b) a dependence on the sign of the By component of the interplanetary magnetic field (IMF): GMDs were larger in the north (south) when IMF By was >0 (<0). A majority of events occurred nearly simultaneously (to within ±3 min) independent of the sign of By as long as |By| ≤ 2 |Bz|. As has been found in earlier studies, IMF Bz was <0 prior to most events. When IMF data from Geotail, Themis B, and/or Themis C in the near-Earth solar wind were used to supplement the time-shifted OMNI IMF data, the consistency of these IMF orientations was improved.

Original languageEnglish (US)
Article numbere2022JA030580
JournalJournal of Geophysical Research: Space Physics
Volume127
Issue number10
DOIs
StatePublished - Oct 2022

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Space and Planetary Science

Keywords

  • geomagnetic disturbances
  • geomagnetic storms
  • geomagnetically induced currents
  • GIC
  • magnetic conjugacy
  • magnetic perturbation events
  • substorms

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