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Magnetic Perturbation Events (MPEs) that cause GICs: Investigating their Interhemispheric Conjugacy and Control by IMF Orientation
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  • Mark J. Engebretson,
  • Laura E. Simms,
  • Vyatcheslav A. Pilipenko,
  • Lilia Bouayed,
  • Mark B. Moldwin,
  • James M. Weygand,
  • Michael D. Hartinger,
  • Zhonghua Xu,
  • C. Robert Clauer,
  • Shane Coyle,
  • Anna Willer,
  • Mervyn P. Freeman,
  • Andrew J. Gerrard
Mark J. Engebretson
Department of Physics, Augsburg University

Corresponding Author:[email protected]

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Laura E. Simms
Department of Physics, Augsburg University
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Vyatcheslav A. Pilipenko
Institute of Physics of the Earth
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Lilia Bouayed
Department of Physics, Augsburg University
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Mark B. Moldwin
University of Michigan-Ann Arbor
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James M. Weygand
Department of Earth, Planetary, and Space Sciences
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Michael D. Hartinger
Space Science Institute
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Zhonghua Xu
Virginia Polytechnic Institute and State University
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C. Robert Clauer
Virginia Polytechnic Institute and State University
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Shane Coyle
Virginia Tech
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Anna Willer
Technical University of Denmark
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Mervyn P. Freeman
British Antarctic Survey
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Andrew J. Gerrard
New Jersey Institute of Technology
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Abstract

Nearly all studies of impulsive magnetic perturbation events (MPEs) that can produce dangerous geomagnetically induced currents (GICs) have used data from the northern hemisphere. In this study we investigated MPE 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): MPEs 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.