The results of an analysis of the east-west magnetic variations at midlatitudes suggest that the net field-aligned currents, which are the integral of the downward and upward field-aligned currents along a meridian, are strongly controlled by the polar ionospheric conductivity. The east-west magnetic disturbances at midlatitudes are expected to be the magnetic effects of the net field-aligned currents in the polar region. We have examined the relation between the auroral electrojet intensity represented by the auroral electrojet (AE) index and the net field-aligned current intensity represented by the east-west magnetic disturbances at midlatitudes. It is deduced from this analysis that the net field-aligned currents are upward on the nightside and downward on the dayside. It is also derived that the net upward field-aligned currents on the nightside are stronger in winter than in summer. This seasonal dependence can be explained by the seasonal variation of the polar cap ionospheric conductivity.