Impact Angle Control of Local Intense dB/dt Variations During Shock-Induced Substorms

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dc.contributor.authorOliveira, Denny M.en
dc.contributor.authorWeygand, James M.en
dc.contributor.authorZesta, Eftyhiaen
dc.contributor.authorNgwira, Chigomezyo M.en
dc.contributor.authorHartinger, Michael D.en
dc.contributor.authorXu, Zhonghuaen
dc.contributor.authorGiles, Barbara L.en
dc.contributor.authorGershman, Daniel J.en
dc.contributor.authorSilveira, Marcos V. D.en
dc.contributor.authorSouza, Vítor M.en
dc.date.accessioned2022-01-05T18:52:11Zen
dc.date.available2022-01-05T18:52:11Zen
dc.date.issued2021-12-01en
dc.date.updated2022-01-05T18:51:57Zen
dc.description.abstractThe impact of interplanetary shocks on the magnetosphere can trigger magnetic substorms that intensify auroral electrojet currents. These currents enhance ground magnetic field perturbations (dB/dt), which in turn generate geomagnetically induced currents (GICs) that can be detrimental to power transmission infrastructure. We perform a comparative study of dB/dt variations in response to two similarly strong shocks, but with one being nearly frontal and the other highly inclined. Multi-instrument analyses by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) and Los Alamos National Laboratory spacecraft show that nightside substorm-time energetic particle injections are more intense and occur faster in the case of the nearly head-on impact. The same trend is observed in dB/dt variations recorded by THEMIS ground magnetometers. THEMIS all-sky imager data show a fast and clear poleward auroral expansion in the first case, which does not clearly occur in the second case. Strong field-aligned currents computed with the spherical elementary current system (SECS) technique occur in both cases, but the current variations resulting from the inclined shock impact are weaker and slower compared to the nearly frontal case. SECS analyses also reveal that geographic areas with dB/dt surpassing the thresholds 1.5 and 5 nT/s, usually linked to high-risk GICs, are larger and occur earlier due to the symmetric compression caused by the nearly head-on impact. These results, with profound space weather implications, suggest that shock impact angles affect the geospace driving conditions and the location and intensity of the subsequent dB/dt variations during substorm activity.en
dc.description.versionPublished versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.1029/2021SW002933en
dc.identifier.eissn1542-7390en
dc.identifier.issn1542-7390en
dc.identifier.issue12en
dc.identifier.orcidXu, Zhonghua [0000-0002-3800-2162]en
dc.identifier.urihttp://hdl.handle.net/10919/107402en
dc.identifier.volume19en
dc.language.isoenen
dc.publisherAmerican Geophysical Unionen
dc.rightsCreative Commons Attribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.subject0201 Astronomical and Space Sciencesen
dc.titleImpact Angle Control of Local Intense dB/dt Variations During Shock-Induced Substormsen
dc.title.serialSpace Weatheren
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.otherJournal Articleen
pubs.organisational-group/Virginia Techen
pubs.organisational-group/Virginia Tech/Engineeringen
pubs.organisational-group/Virginia Tech/Engineering/Electrical and Computer Engineeringen
pubs.organisational-group/Virginia Tech/Post-docsen

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