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Found 2 entries in the Bibliography.


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2021

Geomagnetic Pulsations Driving Geomagnetically Induced Currents

Geomagnetically induced currents (GICs) are driven by the geoelectric field induced by fluctuations of Earth s magnetic field. Drivers of intense GICs are often associated with large impulsive events such as coronal mass ejections. To a lesser extent fluctuations from regular oscillations of the geomagnetic field, or geomagnetic pulsations, have also been identified as possible drivers of GICs. In this work we show that these low-frequency pulsations are directly observed in measured GIC data from power networks. Due to the low-pass nature of GICs, Pc5 and lower-frequency pulsations drive significant GICs for an extended duration even at midlatitudes. Longer-period Ps6-type disturbances apparently not typical of midlatitudes are seen with GIC amplitudes comparable to the peak GIC at storm sudden commencement. The quasi-ac (alternating current) nature of the sustained pulsation driving affects the power system response and cannot be properly modeled using only direct current (dc) models. A further consideration is that the often used dB/dt GIC proxy is biased to the sampling rate of the geomagnetic field measurements used. The dB/dt metric does not adequately characterize GIC activity at frequencies in the low ultralow-frequency (ULF) range, and a frequency-weighted proxy akin to geoelectric field should be used instead.

Heyns, M.; Lotz, S.; Gaunt, C.;

Published by: Space Weather      Published on:

YEAR: 2021     DOI: 10.1029/2020SW002557

space weather; geomagnetic pulsations; geomagnetically induced currents

2020

Ionospheric response at conjugate locations during the 7—8 September 2017 geomagnetic storm over the Europe-African longitude sector

This paper focuses on unique aspects of the ionospheric response at conjugate locations over Europe and South Africa during the 7–8 September 2017 geomagnetic storm including

Habarulema, John; Katamzi-Joseph, Zama; a, Dalia; Nndanganeni, Rendani; Matamba, Tshimangadzo; Tshisaphungo, Mpho; Buchert, Stephan; Kosch, Michael; Lotz, Stefan; Cilliers, Pierre; , others;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2020     DOI: 10.1029/2020JA028307



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