[1] In this paper, we studied the possible relations between incoming meteors, sporadic E (Es) layers, and sporadic (or sudden) sodium atom layers (SSLs) using the data from the FORMOSAT-3/COSMIC constellation, a meteor radar (Wuhan, 31°N, 114°E), and a sodium fluorescent lidar (Hefei, 31.8°N, 117.3°E). From a statistical point of view, a seasonal dependence of SSL correlates well with the annual variation of Es and is also consistent with seasonal meteor deposition except for February and March. It suggests that a "meteor-Es-SSL" chain could be reasonable if the recombination process were taken into consideration. Detailed study on the relationship between electron density profiles provided by the COSMIC radio occultation and the observations of SSLs by the University of Science and Technology of China via lidar illustrates that the appearance of Es accompanying SSL (i.e., 56.3%) is three times greater than that in the "normal" sodium layer. It also indicates that tides play an important role in causing the lower SSLs, which might be able to carry the upper dense electrons and ions in the Es layer formed by wind shear to the lower altitudes through downward phase propagations.

Abstract. Sodium lidar observations of sporadic sodium layers (SSLs) during the past 3 years at a mid-latitude location (Hefei, China, 31.8 • N, 117.3 • E) are reported in this paper. From 64 SSL events detected in about 900 h of observation, an SSL occurrence rate of 1 event every 14 h at our location was obtained. This result, combined with previous studies, reveals that the SSL occurrence can be relatively frequent at some mid-latitude locations. Statistical analysis of main parameters for the 64 SSL events was performed. By examining the corresponding data from an ionosonde, a considerable correlation was found with a Pearson coefficient of 0.66 between seasonal variations of SSL and those of sporadic E (Es) during nighttime, which was in line with the research by Nagasawa and Abo (1995). From comparison between observations from the University of Science and Technology of China (USTC) lidar and from Wuhan Institute of Physics and Mathematics (WIPM) lidar (Wuhan, China, 31 • N, 114 • E), the minimum horizontal range for some events was estimated to be over 500 km.