Articles | Volume 16, issue 6
Ann. Geophys., 16, 698–710, 1998

Special issue: Electrojet

Ann. Geophys., 16, 698–710, 1998

  30 Jun 1998

30 Jun 1998

Equatorial electrojet as part of the global circuit: a case-study from the IEEY

A. T. Kobea1, C. Amory-Mazaudier2, J. M. Do2, H. Lühr3, E. Houngninou1, J. Vassal2, E. Blanc4, and J. J. Curto5 A. T. Kobea et al.
  • 1U. F. R. SSMT / Laboratoire de Physique de l'Atmosphère, 22 B.P. 582 Abidjan 22, Côte d'Ivoire Tel: 225 44 49 82; Fax: 225 44 49 82/44 38 47; e-mail:
  • 2Centre d'Etudes des Environnements Terrestres et Planétaires(CETP), Observatoire de Saint-Maur. 4, avenue de Neptune, F-94107 Saint-Maur-Des-Fossés, France
  • 3Institut für Geophysik und Meteorologie der Technischen Universität Braunschweig, Mendelssohnstrass 3, D-38106 Braunschweig, Germany
  • 4Commissariat à l'Energie Atomique, Laboratoire de Détection et de Géophysique, BP 12, F-91680 Bruyères-le-Châtel, France
  • 5Observatorio de Ebre, E-43520 Roquetes, Tarragona, Spain

Abstract. Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they affect the normal eastward Sq field. This paper presents an analysis of ground magnetic field and ionospheric electrodynamic data related to the geomagnetic storm which occured on 27 May 1993 during the International Equatorial Electrojet Year (IEEY) experiment. This storm-signature analysis on the auroral, mid-latitude and equatorial ground field and ionospheric electrodynamic data leads to the identification of a sensitive response of the equatorial electrojet (EEJ) to large-scale auroral return current: this response consists in a change of the eastward electric field during the pre-sunrise hours (0400-0600 UT) coherently to the high-, mid-, and equatorial-latitude H decrease and the disappearance of the EEJ irregularities between the time-interval 0800-0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA) caused by the high-latitude penetrating electric field. The strengthening of these irregularities attested by the Doppler frequency increase tracks the H component at the equator which undergoes a rapid increase around 0800 UT. The ∆H variations observed at the equator are the sum of the following components: SR, DP, DR, DCF and DT.

Keywords. Equatorial electrojet · Magnetosphere-ionosphere interactions · Electric fields and currents · Auroral ionosphere · Ionospheric disturbances

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