Academic Journal
Occurrence and Causes of Large dB/dt Events and AL Bays in the Pre-Midnight and Dawn Sectors
| العنوان: | Occurrence and Causes of Large dB/dt Events and AL Bays in the Pre-Midnight and Dawn Sectors |
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| المؤلفون: | Milan, S.E., Bower, G.E., Fleetham, A.L., Imber, S.M., Schillings, A., Opgenoorth, H., Gjerloev, J., Paxton, L.J., Vines, S.K., Hubert, Benoît, Hairston, M.R. |
| المصدر: | Journal of Geophysical Research. Space Physics, 129 (10) (2024-10) |
| بيانات النشر: | John Wiley and Sons Inc, 2024. |
| سنة النشر: | 2024 |
| مصطلحات موضوعية: | geomagnetic storms, geomagnetically induced currents, omega bands, substorms, westward electrojet, Geophysics, Space and Planetary Science, Physical, chemical, mathematical & earth Sciences, Space science, astronomy & astrophysics, Earth sciences & physical geography, Physics, Physique, chimie, mathématiques & sciences de la terre, Aérospatiale, astronomie & astrophysique, Sciences de la terre & géographie physique, Physique |
| الوصف: | A necessary condition for the generation of Geomagnetically Induced Currents (GICs) that can pose hazards for technological infrastructure is the occurrence of large, rapid changes in the magnetic field at the surface of the Earth. We investigate the causes of such (Formula presented.) events or “spikes” observed by SuperMAG at auroral latitudes, by comparing with the time-series of different types of geomagnetic activity for the duration of 2010. Spikes are found to occur predominantly in the pre-midnight and dawn sectors. We find that pre-midnight spikes are associated with substorm onsets. Dawn sector spikes are not directly associated with substorms, but with auroral activity occurring within the westward electrojet region. Azimuthally-spaced auroral features drift sunwards, producing Ps6 (10–20 min period) magnetic perturbations on the ground. The magnitude of (Formula presented.) is determined by the flow speed in the convection return flow region, which in turn is related to the strength of solar wind-magnetospheric coupling. Pre-midnight and dawn sector spikes can occur at the same time, as strong coupling favors both substorms and westward electrojet activity; however, the mechanisms that create them seem somewhat independent. The dawn auroral features share some characteristics with omega bands, but can also appear as north-south aligned auroral streamers. We suggest that these two phenomena share a single underlying cause. The associated fluctuations in the westward electrojet produce quasi-periodic negative excursions in the AL index, which can be mis-identified as recurrent substorm intensifications. |
| نوع الوثيقة: | journal article http://purl.org/coar/resource_type/c_6501 article peer reviewed |
| اللغة: | English |
| Relation: | https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2024JA032811; urn:issn:2169-9380; urn:issn:2169-9402 |
| DOI: | 10.1029/2024JA032811 |
| URL الوصول: | https://orbi.uliege.be/handle/2268/325629 |
| Rights: | restricted access http://purl.org/coar/access_right/c_16ec info:eu-repo/semantics/restrictedAccess |
| رقم الانضمام: | edsorb.325629 |
| قاعدة البيانات: | ORBi |
| DOI: | 10.1029/2024JA032811 |
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