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International Journal of Geophysics
Volume 2012, Article ID 648402, 5 pages
Research Article

On a Correlation between the Ionospheric Electric Field and the Time Derivative of the Magnetic Field

1School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA
2IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, USA

Received 11 November 2011; Accepted 20 February 2012

Academic Editor: Yuichi Otsuka

Copyright © 2012 R. R. Ilma et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A correlation of the ionospheric electric field and the time derivative of the magnetic field was noticed over thirty years ago and has yet to be explained. Here we report on another set of examples during the superstorm of November 2004. The electric field in the equatorial ionosphere, measured with the Jicamarca incoherent scatter radar, exhibited a 3 mV/m electric field pulse that was not seen in the interplanetary medium. It was, however, accompanied by a correlation with the time derivative of the magnetic field measured at two points in Peru. Our inclination was to assume that the field was inductive. However, the time scale of the pulse was too short for the magnetic field to penetrate the crust of the Earth. This means that the area threaded by was too small to create the observed electric field by induction. We suggest that the effect was caused by a modulation of the ring current location relative to the Earth due to the electric field. This electric field is required, as the magnetic field lines are considered frozen into the plasma in the magnetosphere. The closer location of the ring current to the Earth in turn increased the magnetic field at the surface.