A statistical analysis of sporadic E layer occurrence in the midlatitude China region

A statistical analysis of sporadic E layer recorded from September 2011 to September 2015 at four Chinese ionospheric sounding stations of Mohe (122.37°E, 53.50°N), Beijing (116.25°E, 40.25°N), Wuhan (114.61°E, 30.53°N), and Hainan (109.13°E, 19.52°N) are presented to investigate the characteristics of sporadic E layer at the middle latitudes over China. The occurrence of the sporadic E layer in mid-latitude China region shows strong dependence on local time and season, consistent with previous studies. The occurrence of the mid-latitude sporadic E layer is prominent at local daytime in summer season. The results also reveal that the post-sunset sporadic E layer is statistically pronounced in mid-latitude China region, possibly related to the nighttime mid-latitude E region irregularities. The mid-latitude sporadic E layer is modulated by atmospheric tidal waves and planetary waves at different latitudes. The occurrence of the mid-latitude sporadic E layer also tends to increase with the level of geomagnetic activity on basis of both the statistical analysis and case study.