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Geomagnetically Induced Currents Caused by Interplanetary Shocks with Different Impact Angles and SpeedsThe occurrence of geomagnetically induced currents (GICs) poses serious threats to modern technological infrastructure. Large GICs result from sharp variations of the geomagnetic field (dB∕dt) caused by changes of large-scale magnetospheric and ionospheric currents. Intense dB∕dt perturbations are known to occur often in high-latitude regions as a result of storm time substorms. Magnetospheric compressions usually caused by interplanetary shocks increase the magnetopause current leading to dB∕dt perturbations more evident in midlatitude to low-latitude regions, while they increase the equatorial electrojet current leading to dB∕dt perturbations in dayside equatorial regions. We investigate the effects of shock impact angles and speeds on the subsequent dB∕dt perturbations with a database of 547 shocks observed at the L1 point. By adopting the threshold of dB∕dt = 100 nT/min, identified as a risk factor to power systems, we find that dB∕dt generally surpasses this threshold when following impacts of high-speed and nearly frontal shocks in dayside high-latitude locations. The same trend occurs at lower latitudes and for all nightside events but with fewer high-risk events. Particularly, we found nine events in equatorial locations with dB∕dt > 100 nT/min. All events were caused by high-speed and nearly frontal shock impacts and were observed by stations located around noon local time. These high-risk perturbations were caused by sudden strong and symmetric magnetospheric compressions, more effectively intensifying the equatorial electrojet current, leading to sharp dB∕dt perturbations. We suggest that these results may provide insights for GIC forecasting aiming at preventing degradation of power systems due to GICs.
Document ID
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Oliveira, D. M.
(Maryland Univ. Baltimore County (UMBC) Baltimore, MD, United States)
Arel, D.
(New Hampshire Univ. Durham, NH, United States)
Raeder, J.
(New Hampshire Univ. Durham, NH, United States)
Zesta, E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Ngwira, C. M.
(Catholic Univ. of America Washington, DC, United States)
Carter, B. A.
(RMIT University Melbourne, Australia)
Yizengaw, E.
(Boston Coll. Boston, MA, United States)
Halford, A. J.
(Aerospace Corp. Chantilly, VA, United States)
Tsurutani, B. T.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Gjerloev, J. W.
(Johns Hopkins Univ. Laurel, MD, United States)
Date Acquired
August 28, 2018
Publication Date
May 18, 2018
Publication Information
Publication: Space Weather
Publisher: American Geophysical Union
Volume: 16
Issue: 6
ISSN: 1539-4956
e-ISSN: 1542-7390
Subject Category
Physics (General)
Report/Patent Number
Funding Number(s)
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