Relative contribution of ionospheric conductivity and electric field to the auroral electrojets

Data from continuous scans of the Chatanika radar beam along the magnetic meridian plane are used to determine the latitudinal profile of height‐integrated ionospheric conductivities and horizontal electric fields, from which the latitudinal distribution of ionospheric currents is deduced. The observations cover invariant latitudes between 62° and 68°, where the IMS Alaska meridian chain of magnetometers was also in operation. Although the conductivities and the electric fields are interrelated, the relative importance of the two in driving the eastward and westward auroral electrojet currents can be assessed. It is found that for moderate and large current densities (i.e., ≳0.2 A/m), the northward electric field strength increases as the magnitude of the eastward electrojet in the evening sector increases. The height‐integrated Hall conductivity stays generally at the level of 10 mhos even when the current density becomes as large as 1 A/m. However, when the eastward electrojet is small, substantial electric fields of 10–20 mV/m may still exist as if the magnetosphere has a persistent voltage source. There appear to be two distinct components to the westward electrojet. In the midnight and early morning sestors (0300 MLT) is dominated by a strong southward electric field.