Contribution of magnetospheric field‐aligned current to geomagnetic bays and Sq fields: A comment on partial ring‐current models

Curved field‐aligned currents in the magnetosphere produce a noticeable geomagnetic effect on the earth's surface not only in the D component but also in the H component. For geomagnetic bays or longitudinal asymmetry of Δ H (deviation in H from its quiet level) during magnetic storms, the contribution from the field‐aligned currents is greater than that of a partial ring current. The Sq field also may be appreciably influenced by the field‐aligned currents associated with the magnetospheric plasma convection.