Double sodium layers observation over Beijing, China

Abstract

The altitude of the sodium layer in the mesosphere and lower thermosphere is usually from 80km to 105km. In this paper, we report a set of double sodium layer (DSL) events observed by sodium lidar over Beijing, China. In these DSL events, the normal sodium layer and secondary sodium layer (SeSL) present separately. There were about 17 DSL events occurred in 319 observation nights during 2009∼2011. All DSL events were observed in spring and summer. The SeSL appeared independently within the altitude range from 105km to 130km. The density of the SeSL is very high. The maximum ratio of peak density and the ratio of column density for the SeSL to the normal sodium layer are up to ∼60% and ∼47%, respectively. The SeSL lasted several hours, and then merged into the normal sodium layer. After the SeSL, a sporadic sodium layer occurred in the normal sodium layer. © 2012 by the American Geophysical Union.