Height comparison of midlatitude E region field‐aligned irregularities and sporadic E Layer

Publisher Website
Google Scholar
Abstract
We present for the first time detailed comparison of heights of MU radar field‐aligned echoes and sporadic E (Es) layer by applying an FM‐CW sounding technique for observing Es virtual height with high spatial (750 m) and time (one minute) resolutions. The production of typical, discrete quasi‐periodic (QP) radar echoes appearing after sunset is closely related to the oscillation of Es height, supporting a theory of the QP echo generation. No Es height oscillations, however, were observed for the QP echoes appearing around midnight. Continuous radar echoes appearing after sunrise are located at 90–100 km heights that are lower than the Es heights (≥100 km), suggesting that a new mechanism other than the gradient‐drift plasma instability is necessary for producing these morning continuous echoes.