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Annual fractions of high-speed streams from principal component analysis of local geomagnetic activity
Responsible organisation
2014 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 119, no 6, p. 4544-4555Article in journal (Refereed) Published
Abstract [en]

We study the latitudinal distribution of geomagnetic activity in 1966–2009 with local geomagnetic activity indices at 26 magnetic observatories. Using the principal component analysis method we find that more than 97% of the variance in annually averaged geomagnetic activity can be described by the two first principal components. The first component describes the evolution of the global geomagnetic activity, and has excellent correlation with, e.g., the Kp/Ap index. The second component describes the leading pattern by which the latitudinal distribution of geomagnetic activity deviates from the global average. We show that the second component is highly correlated with the relative (annual) fraction of high-speed streams (HSS) in solar wind. The latitudinal distribution of the second mode has a high maximum at auroral latitudes, a local minimum at subauroral latitudes and a low maximum at midlatitudes. We show that this distribution is related to the difference in the average location and intensity between substorms related to coronal mass ejections (CMEs) and HSSs. This paper demonstrates a new way to extract useful, quantitative information about the solar wind from local indices of geomagnetic activity over a latitudinally extensive network.

Place, publisher, year, edition, pages
2014. Vol. 119, no 6, p. 4544-4555
Keywords [en]
Solar wind/magnetosphere interactions, Magnetic storms and substorms, Substorms, geomagnetic activity, solar wind, geomagnetic indices, high-speed streams
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:polar:diva-4145DOI: 10.1002/2014JA019958OAI: oai:DiVA.org:polar-4145DiVA, id: diva2:1170874
Available from: 2018-01-04 Created: 2018-01-04 Last updated: 2018-01-04

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Publisher's full texthttp://dx.doi.org/10.1002/2014JA019958
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  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
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  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
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  • text
  • asciidoc
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