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Brightening of onset arc precedes the dipolarization onset: THEMIS observations of two events on 1 March 2008
Kan, J. R.; Li, H.; Wang, C.; Frey, H. U.; Kubyshkina, M. V.; Runov, A.; Xiao, C. J.; Lyu, L. H.; Sun, W.; Li, H (reprint author), Chinese Acad Sci, Natl Space Sci Ctr, Beijing, Peoples R China.
Department空间科学部
Source PublicationANNALES GEOPHYSICAE
2011
Volume29Issue:11Pages:2045-2059
ISSN0992-7689
Language英语
KeywordMagnetospheric Physics Magnetosphere-ionosphere Interactions
AbstractWe present a new M-I coupling model of substorm during southward IMF based on the THEMIS observations of two events on 1 March 2008. The first event (E-1) was classified as a pseudo-breakup: brightening of the onset arc preceded the first dipolarization onset by similar to 71 +/- 3 s, but the breakup arcs faded within similar to 5 min without substantial poleward expansion and the dipolarization stopped and reversed to thinning. The second event (E-2) was identified as a substorm: brightening of the second onset arc preceded the second dipolarization onset by similar to 80 +/- 3 s, leading to a full-scale expanding auroral bulge during the substorm expansion phase for similar to 20 min. The Alfven travel time from the ionosphere to the dipolarization onset region is estimated at similar to 69.3 s in E-1; at similar to 80.3 s in E-2, which matched well with the observed time delay of the dipolarization onset after the brightening of the onset arc, respectively in E-1 and E-2. Brightening of the onset arc precedes the dipolarization onset suggest that the onset arc brightening is caused by the intense upward field-aligned currents originating from the divergence of the Cowling electrojet in the ionosphere. The Cowling electrojet current loop (CECL) is formed to close the field-aligned currents at all times. The closure current in the Alfven wavefront is anti-parallel to the cross-tail current. Dipolarization onset occurs when the Alfven wavefront incident on the near-Earth plasma sheet to disrupt the cross-tail current in the dipolarization region. Slow MHD waves dominate the disruption of the cross-tail current in the dipolarization region.; We present a new M-I coupling model of substorm during southward IMF based on the THEMIS observations of two events on 1 March 2008. The first event (E-1) was classified as a pseudo-breakup: brightening of the onset arc preceded the first dipolarization onset by similar to 71 +/- 3 s, but the breakup arcs faded within similar to 5 min without substantial poleward expansion and the dipolarization stopped and reversed to thinning. The second event (E-2) was identified as a substorm: brightening of the second onset arc preceded the second dipolarization onset by similar to 80 +/- 3 s, leading to a full-scale expanding auroral bulge during the substorm expansion phase for similar to 20 min. The Alfven travel time from the ionosphere to the dipolarization onset region is estimated at similar to 69.3 s in E-1; at similar to 80.3 s in E-2, which matched well with the observed time delay of the dipolarization onset after the brightening of the onset arc, respectively in E-1 and E-2. Brightening of the onset arc precedes the dipolarization onset suggest that the onset arc brightening is caused by the intense upward field-aligned currents originating from the divergence of the Cowling electrojet in the ionosphere. The Cowling electrojet current loop (CECL) is formed to close the field-aligned currents at all times. The closure current in the Alfven wavefront is anti-parallel to the cross-tail current. Dipolarization onset occurs when the Alfven wavefront incident on the near-Earth plasma sheet to disrupt the cross-tail current in the dipolarization region. Slow MHD waves dominate the disruption of the cross-tail current in the dipolarization region.
Indexed BySCI ; EI
Funding Project中国科学院空间科学与应用研究中心
Document Type期刊论文
Identifierhttp://ir.nssc.ac.cn/handle/122/3242
Collection空间科学部
Corresponding AuthorLi, H (reprint author), Chinese Acad Sci, Natl Space Sci Ctr, Beijing, Peoples R China.
Recommended Citation
GB/T 7714
Kan, J. R.,Li, H.,Wang, C.,et al. Brightening of onset arc precedes the dipolarization onset: THEMIS observations of two events on 1 March 2008[J]. ANNALES GEOPHYSICAE,2011,29(11):2045-2059.
APA Kan, J. R..,Li, H..,Wang, C..,Frey, H. U..,Kubyshkina, M. V..,...&Li, H .(2011).Brightening of onset arc precedes the dipolarization onset: THEMIS observations of two events on 1 March 2008.ANNALES GEOPHYSICAE,29(11),2045-2059.
MLA Kan, J. R.,et al."Brightening of onset arc precedes the dipolarization onset: THEMIS observations of two events on 1 March 2008".ANNALES GEOPHYSICAE 29.11(2011):2045-2059.
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