Spectral characteristics of auroral F region irregularities were studied by the use of high-resolution (~35 m) density measurements made by the retarding potential analyzer (RPA) on board the Atmosphere Explorer D (AE-D) satellite during two orbits when the satellite was traversing the high-latitude ionosphere in the evening sector. Coordinated DMSP passes provided synoptic coverage of auroral activity. The auroral energy input was estimated by intergrating the low-energy electron (LEE) data on AE-D. It was found that the one-dimensional in situ spectral index (p1) of the irregularities at scale lengths of <1 km showed considerable steepening in regions of large auroral acceleration events with &rgr;1 values of ~-3. This is interpreted as resulting from the effects of E region conductivity on the F region irregularity structure. The regions in between the precipitation structures, where presumably the E region conductivity was small, were generally associated with large shears in the horizontal E-W drifts and large velocities, as measured by the ion drift meter on board AE-D. The maximum drifts measured were ~2 km s-1, corresponding to an electric field of 100 mV m-1. The large-velocity regions were also associated with substantial ion heating and electron density depletions. The largest shear magnitudes observed were ~80 m s-1 km-1, and the shear gradient scale lengths were ~10 km, which was approximately the resolution of the ion drift meter data set used. The spectral characteristics of irregularities in the large, variable flow regions were very different, with p1 being ~-1. Since these regions were also associated with the largest irregularity amplitudes, it seemed probable that either the velocity shears or, alternatively, the large velocities provided a source of irregularities in the auroral F region ionosphere. Current work on plasma instabilities related to velocity shears and two-dimensional fluid turbulence is briefly summarized and critically compared to the findings of the present study.