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dc.contributor.authorØstgaard, Nikolai
dc.contributor.authorReistad, Jone Peter
dc.contributor.authorTenfjord, Paul
dc.contributor.authorLaundal, Karl Magnus
dc.contributor.authorRexer, Theresa
dc.contributor.authorHaaland, Stein
dc.contributor.authorSnekvik, Kristian
dc.contributor.authorHesse, Michael
dc.contributor.authorMilan, Stephen Eric
dc.contributor.authorOhma, Anders
dc.PublishedØstgaard N, Reistad JP, Tenfjord PAR, Laundal KM, Rexer T, Haaland SE, Snekvik K, Hesse M, Milan SE, Ohma A. The asymmetric geospace as displayed during the geomagnetic storm on 17 August 2001. Annales Geophysicae. 2018;36(6):1577-1596eng
dc.description.abstractPrevious studies have shown that conjugate auroral features are displaced in the two hemispheres when the interplanetary magnetic field (IMF) has a transverse (Y) component. It has also been shown that a BY component is induced in the closed magnetosphere due to the asymmetric loading of magnetic flux in the lobes following asymmetric dayside reconnection when the IMF has a Y component. The magnetic field lines with azimuthally displaced footpoints map into a “banana”-shaped convection cell in one hemisphere and an “orange”-shaped cell in the other. Due to the Parker spiral our system is most often exposed to a BY-dominated IMF. The dipole tilt angle, varying between ±34∘, leads to warping of the plasma sheet and oppositely directed BY components in dawn and dusk in the closed magnetosphere. As a result of the Parker spiral and dipole tilt, geospace is asymmetric most of the time. The magnetic storm on 17 August 2001 offers a unique opportunity to study the dynamics of the asymmetric geospace. IMF BY was 20–30 nT and tilt angle was 23∘. Auroral imaging revealed conjugate features displaced by 3–4 h magnetic local time. The latitudinal width of the dawnside aurora was quite different (up to 6∘) in the two hemispheres. The auroral observations together with convection patterns derived entirely from measurements indicate dayside, lobe and tail reconnection in the north, but most likely only dayside and tail reconnection in the Southern Hemisphere. Increased tail reconnection during the substorm expansion phase reduces the asymmetry.en_US
dc.publisherCopernicus Publicationsen_US
dc.rightsAttribution CC BYeng
dc.titleThe asymmetric geospace as displayed during the geomagnetic storm on 17 August 2001en_US
dc.typePeer reviewed
dc.typeJournal article
dc.rights.holderCopyright 2018 The Author(s)en_US
dc.source.journalAnnales Geophysicae

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