Intensification of the Cowling current in the global MHD simulation model

Abstract

We examine the effects of the ionospheric conductance on the intensification of the westward electrojet current in the ionosphere based on the piecewise parabolic method with a Lagrangian remap (PPMLR) global MHD simulation model. The ionospheric conductance is empirically linked to the plasma pressure in the plasma sheet. The simulation results are consistent with observations: When the Pedersen and Hall conductances are small, the ionospheric current shows a two-cell pattern; when the conductances increase and the ratio ΣH/ΣP ≥ 2, an intense westward electrojet appears in the midnight sector. This intense westward electrojet is the Cowling current driven by the induced southward electric field due to the blockage of the northward Hall current from closure in the equatorial plasma sheet. The simulation shows the development of the Cowling electrojet is essential to the intensification of the westward electrojet in the ionosphere. Copyright 2011 by the American Geophysical Union.