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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 7
Ann. Geophys., 12, 625–635, 1994
© European Geosciences Union 1994
Ann. Geophys., 12, 625–635, 1994
© European Geosciences Union 1994

  30 Jun 1994

30 Jun 1994

A case study of storm commencement and recovery plasmaspheric electric fields near L=2.5 at equinox

H. F. Balmforth, M. A. Clilverd, and A. J. Smith H. F. Balmforth et al.

Abstract. Data from the VLF Doppler experiment at Faraday, Antarctica (65° S, 64° W) are used to study the penetration of the high-latitude convection electric field to lower latitudes during severely disturbed conditions. Alterations of the electric field at L-values within the range 2.0 - 2.7 are studied for two cases at equinox (10 - 12 September 1986 and 1 - 3 May 1986). The recovery of the electric field is found to be approximately an exponential function of time. Values for the equatorial meridional E×B drift velocity, inferred from the data, are used as inputs to a model of the plasmasphere and ionosphere. The model and experimental results are used to investigate the post-storm alteration of ionospheric coupling processes. The magnitude of the effect of ionosphere-plasmasphere coupling fluxes on NmF2 values and the O+-H+ transition height is dependent on the local time of storm commencement, and on the orientation of the electric field. The coupling fluxes appear to have a maximum influence on ionospheric content during the main phase of geomagnetic activity that produces outward motion of plasmaspheric whistler ducts.

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