On the electrical structure of airglow depletion/height layer bands over Arecibo

Using a combination of airglow images and incoherent scatter radar data, we have explored the electrical structure of the airglow depleted, height lay er bands over a mid-latitude site. We find a reproducible electrical signat ure in both components of the electric field in all events studied. The mos t pronounced feature is a large northward/upward electric field in the hear t of the structure. The latter is identical to the radially outward field r eported for mid-latitude conjugate electric fields [Saito et al., 1995], fo und to trace the poleward edge of the equatorial anomaly. We favorably comp are the Arecibo drift to a typical satellite event. These electric fields m ay reflect a nonlinear evolved state of the Perkins instability or some, as yet, unexplained coupling between atmospheric motion and the plasma embedd ed in it. We show here that the F-region Pedersen conductivity is much lowe r in these structures than outside and suggest that this is related to a po larization electric field inside the structure.