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On the influence of open magnetic flux on substorm intensity: Ground- and space-based observations

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journal contribution
posted on 2016-02-02, 13:39 authored by L. B. N. Clausen, Stephen Eric Milan, J. B. H. Baker, J. M. Ruohoniemi, K-H. Glassmeier, J. C. Coxon, B. J. Anderson
[1] Using the location of maximum region 1 current determined by the Active Magnetosphere and Planetary Electrodynamics Response Experiment as a proxy for the open/closed field line boundary, we monitor the evolution of the amount of open magnetic flux inside the magnetosphere during 772 substorms. We then divide all substorms into three classes, depending on the amount of open flux at expansion phase onset. Studying the temporal variations during the substorms of each class for a number of related geophysical parameters, we find that substorms occurring while the amount of open flux is large are generally more intense. By intense we mean that the auroral electrojet, region 1 current, auroral brightness, tail dipolarization and flow speed, ground magnetic signatures, Pi2 wave power, as well as the intensity and extent of the substorm current wedge (SCW) are all larger than during substorms that occur on a contracted polar cap. The SCW manifests itself as an intensification of the nightside R1 and R2 current system after onset. Our analysis shows that to dispose of large amounts of accumulated open magnetic flux, large substorms are triggered in the terrestrial magnetosphere.

History

Citation

Journal Of Geophysical Research-space Physics, 2013, 118 (6), pp. 2958-2969 (12)

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

  • VoR (Version of Record)

Published in

Journal Of Geophysical Research-space Physics

Publisher

American Geophysical Union (AGU)

issn

2169-9380

Acceptance date

2013-04-29

Copyright date

2013

Available date

2016-02-02

Publisher version

http://onlinelibrary.wiley.com/doi/10.1002/jgra.50308/abstract

Language

en