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Nighttime magnetic perturbation events observed in Arctic Canada: 3. Occurrence and amplitude as functions of magnetic latitude, local time, and magnetic disturbances
  • +9
  • Mark J. Engebretson,
  • Vyacheslav A. Pilipenko,
  • Erik S. Steinmetz,
  • Mark B. Moldwin,
  • Martin Connors,
  • David H Boteler,
  • Howard J. Singer,
  • Hermann J. Opgenoorth,
  • Audrey Schillings,
  • Ohtani Shin,
  • Jesper W. Gjerloev,
  • Christopher T. Russell
Mark J. Engebretson
Department of Physics, Augsburg University, Department of Physics, Augsburg University

Corresponding Author:[email protected]

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Vyacheslav A. Pilipenko
Space Research Institute, Space Research Institute
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Erik S. Steinmetz
Department of Computer Science, Augsburg University, Department of Computer Science, Augsburg University
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Mark B. Moldwin
University of Michigan-Ann Arbor, University of Michigan-Ann Arbor
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Martin Connors
Athabasca University, Athabasca University
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David H Boteler
Natural Resources Canada, Natural Resources Canada
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Howard J. Singer
National Oceanic and Atmospheric Administration (NOAA), National Oceanic and Atmospheric Administration (NOAA)
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Hermann J. Opgenoorth
Umeå University, Umeå University
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Audrey Schillings
Swedish Institute of Space Physics, Swedish Institute of Space Physics
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Ohtani Shin
Applied Physics Lab, Applied Physics Lab
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Jesper W. Gjerloev
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Christopher T. Russell
University of California Los Angeles, University of California Los Angeles
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Rapid changes of magnetic fields associated with nighttime magnetic perturbation events (MPEs) with amplitudes |ΔB| of hundreds of nT and 5-10 min periods can induce geomagnetically-induced currents (GICs) that can harm technological systems. In this study we compare the occurrence and amplitude of nighttime MPEs with |dB/dt| ≥ 6 nT/s observed during 2015 and 2017 at five stations in Arctic Canada ranging from 75.2° to 64.7° in corrected geomagnetic latitude (MLAT) as functions of magnetic local time (MLT), the SME and SYM/H magnetic indices, and time delay after substorm onsets. Although most MPEs occurred within 30 minutes after a substorm onset, ~10% of those observed at the four lower latitude stations occurred over two hours after the most recent onset. A broad distribution in local time appeared at all 5 stations between 1700 and 0100 MLT, and a narrower distribution appeared at the lower latitude stations between 0200 and 0700 MLT. There was little or no correlation between MPE amplitude and the SYM/H index; most MPEs at all stations occurred for SYM/H values between -40 and 0 nT. SME index values for MPEs observed more than 1 hour after the most recent substorm onset fell in the lower half of the range of SME values for events during substorms, and dipolarizations in synchronous orbit at GOES 13 during these events were weaker or more often nonexistent. These observations suggest that substorms are neither necessary nor sufficient to cause MPEs, and hence predictions of GICs cannot focus solely on substorms.
Mar 2021Published in Space Weather volume 19 issue 3. 10.1029/2020SW002526