Title: Backscatter radar measurements of storm-time electric field changes in the equatorial electrojet
Abstract: The mean Doppler frequency (f̄D) of the VHP backscatter radar signals from type II plasma irregularities in the equatorial electrojet is a measure of the driving electric field in the electrojet. The measured Doppler frequency values are used to delineate the complex time variations of the electric field and current in the equatorial electrojet during the two geomagnetic storms of 25 April and 18 September in 1979. Using a recently evolved empirical method, the ionospheric and the magnetospheric current contributions to the storm-time surface magnetic field perturbations at Thumba have been estimated; and the characteristic time variations during the initial, main and recovery phases of the magnetic storms are presented. The most significant conclusions of the present study are: (a) the daytime SSC-related increases in ΔH at electrojet latitudes have a large contribution from an impulsive change of electrojet electric field during the SSC; (b) during the initial phase, both the magnetospheric current and electrojet current exhibit rapid fluctuations which are in antiphase; (c) the Dst, values seem to underestimate, by nearly a factor of two, the asymmetric or partial ring current contribution around the time when the main phase decrease in AH reaches its peak level; and (d) the ionosphere and magnetosphere seem to respond as a single electrodynamic system to the electrical disturbances of all scales which originate in the interaction of solar wind with the outer magnetosphere.
Publication Year: 1981
Publication Date: 1981-08-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 42
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