Inferred vertical ion velocities associated with intermediate layers

This paper explores one aspect of ion-neutral coupling in the lower thermosphere. Using the continuity equation, we have developed a procedure to estimate the nighttime E-region vertical ion velocities from density observations obtained by the Arecibo Observatory. The technique is viable when adequate signal-to-noise ratios are present (e.g., when intermediate layers are present). Assuming that horizontal neutral winds are primarily responsible for intermediate layer observations, the calculated velocities may be used to infer information regarding the neutral wind field. The variations observed in the calculated vertical ion velocity may result from a variety of sources including fine-scale structures in the neutral wind, electric field effects or the coupling of the two. (C) 2002 Elsevier Science Ltd. All rights reserved.