Space Science Reviews

, Volume 28, Issue 2, pp 121–190

Energy coupling between the solar wind and the magnetosphere

  • S. -I. Akasofu

DOI: 10.1007/BF00218810

Cite this article as:
Akasofu, S.I. Space Sci Rev (1981) 28: 121. doi:10.1007/BF00218810


This paper describes in detail how we are led to the first approximation expression for the solar wind-magnetosphere energy coupling function ɛ, which correlates well with the total energy consumption rate UTof the magnetosphere. It is shown that ɛ is the primary factor which controls the time development of magnetospheric substorms and storms. The finding of this particular expression ɛ indicates how the solar wind couples its energy to the magnetosphere; the solar wind and the magnetosphere constitute a dynamo. In fact, the power P generated by the dynamo can be identified as ɛ by using a dimensional analysis. Furthermore, the finding of ɛ indicates that the magnetosphere is closer to a directly driven system than to an unloading system which stores the generated energy before converting it to substorm and storm energies. Therefore, the finding of ɛ and its implications have considerably advanced and improved our understanding of magnetospheric processes. The finding of ɛ has also led us to a few specific future problems in understanding relationships between solar activity and magnetospheric disturbances, such as a study of distortion of the solar current disk and the accompanying changes of ɛ. It is also pointed out that one of the first tasks in the energy coupling study is an improvement of the total energy consumption rate UTof the magnetosphere. Specific steps to be taken in this study are suggested.

Copyright information

© D. Reidel Publishing Co. 1981

Authors and Affiliations

  • S. -I. Akasofu
    • 1
  1. 1.Geophysical Institute, University of AlaskaFairbanksUSA

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