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Ionospheric–magnetospheric contributions to storm-time magnetic field changes near dip equator


Experimental identification of the electric current systems in the ionosphere and magnetosphere during magnetic storms is a fundamental problem. We report here a new approach to resolving the relative contributions of ionospheric and magnetospheric currents to the storm-time geomagnetic field variations at equatorial latitudes. In this approach, the VHF backscatter radar-measured electric field changes in the equatorial electrojet and the simultaneous surface magnetic field changes are analysed to determine quantitatively the ionospheric contribution ΔFI to the storm-time geomagnetic field perturbation ΔFD. The magnetospheric contribution ΔFM is then determined from: ΔFDFIFM (1) This method has yielded extremely interesting results for the magnetic storm of 15 February 1978. It has a great potential for providing valuable new insights into the nature and time evolution of the complex storm-time current systems in the ionosphere and magnetosphere.

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Reddy, C., Somayajulu, V. & Viswanathan, K. Ionospheric–magnetospheric contributions to storm-time magnetic field changes near dip equator. Nature 281, 471–474 (1979).

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