Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.585 IF 1.585
  • IF 5-year value: 1.698 IF 5-year
    1.698
  • CiteScore value: 1.62 CiteScore
    1.62
  • SNIP value: 0.820 SNIP 0.820
  • IPP value: 1.52 IPP 1.52
  • SJR value: 0.781 SJR 0.781
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 83 Scimago H
    index 83
  • h5-index value: 24 h5-index 24
Volume 18, issue 9
Ann. Geophys., 18, 1128–1144, 2000
https://doi.org/10.1007/s00585-000-1128-1
© European Geosciences Union 2000

Special issue: IXe EISCAT

Ann. Geophys., 18, 1128–1144, 2000
https://doi.org/10.1007/s00585-000-1128-1
© European Geosciences Union 2000

  30 Sep 2000

30 Sep 2000

Nonlinear model of short-scale electrodynamics in the auroral ionosphere

J.-M. A. Noël1, J.-P. St.-Maurice1, and P.-L. Blelly2 J.-M. A. Noël et al.
  • 1Department of Physics and Astronomy, The University of Western-Ontario, London, Ontario, Canada
  • 2Centre d'étude spatiale des rayonnements, Toulouse, France

Abstract. The optical detection of auroral subarcs a few tens of m wide as well as the direct observation of shears several m/s per m over km to sub km scales by rocket instrumentation both indicate that violent and highly localized electrodynamics can occur at times in the auroral ionosphere over scales 100 m or less in width. These observations as well as the detection of unstable ion-acoustic waves observed by incoherent radars along the geomagnetic field lines has motivated us to develop a detailed time-dependent two-dimensional model of short-scale auroral electrodynamics that uses current continuity, Ohm's law, and 8-moment transport equations for the ions and electrons in the presence of large ambient electric fields to describe wide auroral arcs with sharp edges in response to sharp cut-offs in precipitation (even though it may be possible to describe thin arcs and ultra-thin arcs with our model, we have left such a study for future work). We present the essential elements of this new model and illustrate the model's usefulness with a sample run for which the ambient electric field is 100 mV/m away from the arc and for which electron precipitation cuts off over a region 100 m wide. The sample run demonstrates that parallel current densities of the order of several hundred µA m-2 can be triggered in these circumstances, together with shears several m/s per m in magnitude and parallel electric fields of the order of 0.1 mV/m around 130 km altitude. It also illustrates that the local ionospheric properties like densities, temperature and composition can strongly be affected by the violent localized electrodynamics and vice-versa.

Key words: Ionosphere (auroral ionosphere, electric fields and currents, ionosphere-magnetosphere interactions)

Publications Copernicus
Special issue
Download
Citation