|
|
 |
|
|
Ann. Geophys., 24, 515-527, 2006
www.ann-geophys.net/24/515/2006/
© European Geosciences Union 2006
The field of the equatorial electrojet from CHAMP data
J.-L. Le Mouël1, P. Shebalin2, and A. Chulliat1
1Laboratoire de Géomagnétisme, Institut de Physique du Globe de Paris, 4 place Jussieu 75252 Paris cedex 05, France
2International Institute of Earthquake Prediction Theory and Mathematical Geophysics, Moscow 113556, Russia
Abstract. We apply a simple linear transform, the along-track second derivative,
to four years of scalar and vectorial data from the CHAMP satellite. This
transform, reminiscent of techniques used in the interpretation of
aeromagnetic surveys, is applied either to the geocentric spherical
components of the field or to its intensity. After averaging in time
and space, we first produce a map of the crustal field, then maps of
the equatorial electrojet field at all local times and all universal
times. The seasonal variation of the electrojet, its evolution with
the solar cycle, and the effect of geomagnetic activity are discussed. The
variation of the electrojet with longitude, an intriguing feature
revealed by satellite data, is described in some detail, and it is
shown that this longitude dependance is stable in time. The existence
of a counterelectrojet in the morning, everywhere except over the
Pacific Ocean, is established. The signatures of closure electric
currents and of interhemispheric currents are also evidenced.
Full Article in PDF (4069 KB) |
|
|
