DOI: 10.1029/2017JA025147
Scopus记录号: 2-s2.0-85050294138
论文题名: Tailward Propagation of Magnetic Energy Density Variations With Respect to Substorm Onset Times
作者: Coxon J.C. ; Freeman M.P. ; Jackman C.M. ; Forsyth C. ; Rae I.J. ; Fear R.C.
刊名: Journal of Geophysical Research: Space Physics
ISSN: 21699380
出版年: 2018
卷: 123, 期: 6 起始页码: 4741
结束页码: 4754
语种: 英语
英文关键词: current disruption model
; magnetic energy density
; magnetotail
; magnetotail lobes
; substorms
英文摘要: During geomagnetic substorms, around 1015 J of energy is extracted from the solar wind and processed by the Earth's magnetosphere. Prior to the onset of substorm expansion phases, this energy is thought to be largely stored as an increase in the magnetic field in the magnetotail lobes. However, how, when, and where this energy is stored and released within the magnetotail is unclear. Using data from the Cluster spacecraft and substorm onsets from Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE), we examine the variation in the lobe magnetic energy density with respect to substorm onset for 541 isolated onsets. Based on a cross-correlation analysis and a simple model, we deduce the following: On average, the magnetic energy density increases approximately linearly in the hour preceding onset and decreases at a similar rate after onset. The timing and magnitude of these changes varies with downtail distance, with observations from the mid-tail (X ⪅ −9 RE) showing larger changes in the magnetic energy density that occur ∼20 min after changes in the near-tail (X ⪆ −9 RE). The decrease in energy density in the near-tail region is observed before the ground onset identified by SOPHIE, implying that the substorm is driven from the magnetotail and propagates into the ionosphere. The implication of these results is that energy in the near-tail region is released first during the substorm expansion phase, with energy conversion propagating away from the Earth with time. ©2018. The Authors. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/113826
Appears in Collections: 气候减缓与适应
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作者单位: Department of Physics and Astronomy, University of Southampton, Southampton, United Kingdom; British Antarctic Survey, Cambridge, United Kingdom; UCL Mullard Space Science Laboratory, Dorking, United Kingdom
Recommended Citation:
Coxon J.C.,Freeman M.P.,Jackman C.M.,et al. Tailward Propagation of Magnetic Energy Density Variations With Respect to Substorm Onset Times[J]. Journal of Geophysical Research: Space Physics,2018-01-01,123(6)