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

Abstract

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 ΔF_I to the storm-time geomagnetic field perturbation ΔF _D. The magnetospheric contribution ΔF_M is then determined from: ΔF_D=ΔF_I+ΔF_M (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.