Loading-unloading processes in the nightside ionosphere

EI Kallio*, T.I. Pulkkinen, HEJ Koskinen, A Viljanen, JA Slavin, K Ogilvie

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review


The loading-unloading processes during magnetospheric substorms are examined using the 'IL index' from the IMAGE magnetometer chain together with solar wind and IMF data from the WIND spacecraft. The IL index is a local, midnight sector, AL index. Energy input throughout the substorm is evaluated by integrating the epsilon parameter from the start of the growth phase until the end of the substorm. Energy dissipated in the ionosphere is estimated by integrating the IL index from the substorm onset to the end of the substorm. We show that the best correlation with the energy dissipated in the ionosphere is given by the energy input to the system after the substorm onset. Hence, we con elude that the energy loaded during the growth phase is necessary for the magnetospheric reconfiguration before the substorm onset, but that the size of the substorm as measured by the IL index is mostly governed by the direct energy input during the expansion phase.

Original languageEnglish
Pages (from-to)1627-1630
Number of pages4
JournalGeophysical Research Letters
Issue number11
Publication statusPublished - 1 Jun 2000
MoE publication typeA1 Journal article-refereed



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