Statistical survey on sawtooth events, SMCs and isolated substorms

N. Partamies*, T. I. Pulkkinen, R. L. McPherron, K. McWilliams, C. R. Bryant, E. Tanskanen, H. J. Singer, G. D. Reeves, M. F. Thomsen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review


Solar wind driving can cause a variety of different responses in the magnetosphere. Strong and steady driving during geomagnetic storms may result in sawtooth events. Strong to moderate driving may be followed by either sawtooth events or steady magnetospheric convection (SMC) events. Lower solar wind energy input typically leads to the formation of isolated non-storm substorms. This study uses superposed epoch analysis to reveal the typical properties of these three event groups as well as their similarities and differences. We use IMF and solar wind parameters, as well as ground-based indices (AL, SYM-H, ASY-H, PCN) to examine the level of solar wind driving and its response in the magnetosphere. Our results show that sawtooth events are associated with the strongest ionospheric activity. The subgroups of events during constant solar wind E-gamma show that the key difference between the events is the average solar wind speed. Particularly, the high activity during sawtooth events is driven by high solar wind speed, while the lowest average speed during the SMCs may explain the lack of substorm activity during the steady convection periods. (C) 2009 COSPAR. Published by Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)376-384
Number of pages9
JournalAdvances in Space Research
Issue number3
Publication statusPublished - 4 Aug 2009
MoE publication typeA1 Journal article-refereed


  • M-I coupling
  • Substorm
  • Steady magnetospheric convection
  • Sawtooth event

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