Open AccessRole of solar wind dynamic pressure in driving ionospheric Joule heating
Author(s) -
Palmroth M.,
Pulkkinen T. I.,
Janhunen P.,
McComas D. J.,
Smith C. W.,
Koskinen H. E. J.
Publication year - 2004
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004ja010529
Subject(s) - joule heating , dynamic pressure , solar wind , ionosphere , interplanetary magnetic field , magnetohydrodynamics , geophysics , physics , atmospheric sciences , environmental science , meteorology , mechanics , magnetic field , quantum mechanics
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.