“…Neutralization of metal ions concentrated by wind shear mechanism in the lower E region is given as a possible explanation for formation of Ns layers (Axford, ). The lidar measurements of the neutral Na atoms concentration over low‐ and high‐latitude stations have been carried out for several decades (e.g., Clemesha et al, ; Clemesha, ; Collins et al, ; Sarkhel, Raizada, et al, , ; Sarkhel et al, , ; Takahashi et al, ; Tsuda et al, , ). Na lidar observations from Arecibo Observatory (Kane et al, ) revealed the occurrence of a different type of sporadic Na layer, which was very different in appearance from normal Ns layers and occurred much less frequently.…”