Field‐aligned currents in high latitudes estimated from Millstone Hill Radar observations of ion drifts

A simple scheme has been developed to estimate the global distribution of field‐aligned currents by using electric field measurements by an incoherent scatter radar at Millstone Hill. The combination of the electric field data and a realistic, quiet‐time model of the ionospheric conductivity gives horizontal currents in the ionosphere. The divergence of the ionospheric currents then yields the distribution of the field‐aligned currents. This method is applied to two quiet days in May and July 1978. The field‐aligned currents obtained are consistent with TRIAD satellite observations. The peak location of the global field‐aligned current intensity and the spatial distribution of field‐aligned currents near midnight appear to vary between these two magnetically quiet days.