Estimation of ionospheric electrodynamic parameters using ionospheric conductance deduced from Bremsstrahlung X ray image data

Various ionospheric electrodynamic parameters for the period July 23-24, 1983, are calculated by using ground magnetic records from a total of 88 stations in the northern hemisphere. Several important conclusions of this study are as follows: (1) the poleward portion of the westward electrojet in the morning sector is dominated by the electric field, while its equatorward portion is dominated by the ionospheric conductance; (2) during a quiet or moderately disturbed period, the major electric potential pattern is roughly circumscribed by the auroral zone conductance belt with the subauroral zone being a substantially lower electric field region; (3) the global pattern of the equivalent current system resembles the electrical potential distribution during summer conditions; (4) the electric potential distribution consists generally of a smooth and well-defined two-cell convection pattern without any significantly localized structure; (5) a sunward convection flow is clearly identified over the polar cap region during strongly northward IMF periods; (6) during strongly northward IMF periods, significant currents and Joule dissipation are observed in the polar cap region, indicating that the magnetosphere is far from its ground state; (7) the regions of intense Joule heating are generally confined to relatively narrow belts along the auroral electrojets, with the major heating region in the westward electrojet region shifted poleward and the one in the eastward electrojet region shifted equatorward; (8) the presently available statistical conductance models can be used, as a first approximation, to study global-scale polar ionospheric electrodynamics