The observed magnetospheric convection field at ionospheric heights is simulated by a simple analytic quasi-static electric potential field. The particular, the transition region within the auroral zone where the meridional electric field component reverses is brought into close agreement with Heppner's (1977) observations. The location of zero meridional electric field strength in the model is compared with the observed Harang discontinuity (Maynard, 1974), where the zonal plasma flow reverses. The field-aligned electric currents associated with the model electric field occur within two regions. In region 1, within the auroral zone, maximum ouflow out of the ionosphere occurs at 1600 LT. In region 2, equatorward of the auroral zone, maximum ouflow is near 0700 LT, consistent with measurements of Iijima and Potemra (1976). |