Magnetospheric substorms are strongly modulated by interplanetary high-speed streams

EI Tanskanen*, JA Slavin, AJ Tanskanen, A Viljanen, TI Pulkkinen, HEJ Koskinen, A Pulkkinen, J Eastwood

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review


The occurrence of substorms was examined over a complete 11-year solar cycle, identifying over 5000 substorms. It was found that high-speed streams strongly modulate the substorm occurrence rate, peak amplitude and ionospheric dissipation in the form of Joule heating and auroral electron precipitation. Substorms occurring during the years of frequent interplanetary high-speed streams ( 1994 and 2003) are 32% more intense, on average, and transfer twice as much magnetic energy to the auroral ionosphere as the substorms occurring during the years of few or no high-speed streams ( 1993, 1995 - 2002). To characterize and to predict the substorm activity we form a new measure, the substorm activity parameter R-su, which we expect to become a powerful tool in analyzing the near-Earth space climate.

Original languageEnglish
Article number16104
Number of pages4
JournalGeophysical Research Letters
Issue number16
Publication statusPublished - 26 Aug 2005
MoE publication typeA1 Journal article-refereed



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