Role of solar wind dynamic pressure in driving ionospheric Joule heating

M. Palmroth, T. I. Pulkkinen, P. Janhunen, D. J. McComas, C. W. Smith, H. E.J. Koskinen

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37 Scopus citations


We investigate the role of the solar wind dynamic pressure on the ionospheric dynamics both observationally and using a global MHD simulation. Using ACE solar wind observations we carry out a statistical superposed epoch analysis, in which we determine the ionospheric response, as characterized by the AE index, to solar wind pressure pulses identified from the ACE solar wind data. We find that under steady southward interplanetary magnetic field the AE index increases 35% in 20 min following the pressure pulse but that no such reaction is observed under steady northward IMF. Second, we determine the ionospheric Joule heating in several events using a global MHD simulation GUMICS-4. We find that the solar wind dynamic pressure and the Joule heating are positively correlated. Finally, we discuss mechanisms linking the dynamic pressure to Joule heating. We find evidence that in the simulation, increasing dynamic pressure increases field-aligned currents, which then increases ionospheric Joule heating.

Original languageEnglish (US)
Article numberA11302
JournalJournal of Geophysical Research: Space Physics
Issue numberA11
StatePublished - Nov 2004
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Space and Planetary Science


  • Ionospheric current systems
  • Ionospheric energy deposition
  • Solar wind-ionosphere interaction


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