In this paper, based on the observations from Langmuir probe (LAP) onboard China Seismo-Electromagnetic Satellite (CSES), annual/semi-annual variations of electron density ( Ne ) measured at 02:00 and 14:00 local time (LT) in topside ionosphere have been analyzed. Results indicated that exhibits an amplification-linear-saturation with increase P10.7 daytime, while roughly linear nighttime. The ...