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Substorms on a contracted auroral oval
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2023 (English)In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 245Article in journal (Refereed) Published
Abstract [en]

The high-latitude magnetic substorms observed at geomagnetic latitudes higher 70° MLAT under the substorm absence at the lower latitudes are known as “substorms on the contracted oval” or “polar” substorms. Such substorms appear during quiet or weakly disturbed space weather conditions. The study of 254 “polar” substorms, recorded at the Scandinavian IMAGE magnetometer chain during the winter seasons of 2010–2020, confirmed a tendency to occur in the late evening (∼19–23 MLT), that is a bit earlier than the “normal” substorms (22–24 MLT). It was found that before the onset of “polar” substorms, like “normal” substorms, there is an increase in the PC-index indicating an energy input into the magnetosphere. We established that “polar” substorms, like “normal” substorms, are accompanied by positive mid-latitude magnetic bays, demonstrating a substorm current wedge (SCW) development. Several “polar” substorms are examined in detail. The ionospheric electrojets and field-aligned currents (FAC) distribution was studied basing on the AMPERE satellites measurements. We found that “polar” substorm onsets are associated with an enhancement of FACs in a localized evening area. Thus, “polar” substorms exhibited the properties, typical for “normal” substorms, so, they could be referred as a specific type of substorms developing under rather quiet space weather conditions.

Place, publisher, year, edition, pages
2023. Vol. 245
Keywords [en]
Magnetospheric substorm, Field aligned currents (FAC), Westward and eastward electrojets, Aurora
National Category
Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:polar:diva-9057DOI: 10.1016/j.jastp.2023.106049OAI: oai:DiVA.org:polar-9057DiVA, id: diva2:1820833
Available from: 2023-12-18 Created: 2023-12-18 Last updated: 2023-12-18Bibliographically approved

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Publisher's full texthttps://www.sciencedirect.com/science/article/pii/S1364682623000470
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Journal of Atmospheric and Solar-Terrestrial Physics
Fusion, Plasma and Space Physics

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CiteExportLink to record
Permanent link

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Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf