Characteristics Of Variation And Disturbances In Ionosphere In Low Latitude (Hainan) Region

Characteristics of variation and disturbances in low-latitude ionosphere were investigated based on the data observed in Hainan under different magnetic activities and solar activities including variations and disturbances of parameters in different ionospheric layers, behaviors of plasma drift and a comparison with other low-latitude ionospheric station. The disturbance propagations from high to low latitude region during magnetic storm time are also investigated with analyzing the data obtained from the East-Asian high-middle latitude stations. Especially, the ionospheric electric field in Hainan was studied according to the ionospheric plasma drift velocity by removing the neutral wind effect. Several influence factors to result plasma drift in Hainan were analyzed.In this paper the characteristics of ionospheric parameters variation were analyzed systematically and some new results in storm-time such as seasonal behaviors were obtained; it is the first time to investigate the ionospheric drift behavior in Hainan and some new results was obtained, the relationships between each two plasma drift velocity components in storm time in Hainan were found and the electric filed variation in Hainan ionosphere also was obtained; the results also show that there are big differences of the ionosphere parameters BO and Bl obtained from the data with that obtained from the IRI-2001 applied for Hainan; a new phenomena was found during a strong magnetic storm, that a layer with very strong electron density and density grad was found during the recovery phase of the storm, its horizontal scale is beyond 100km and temporal scale is about 2 hours, this phenomena repeated 3 times continuously. A type of negative disturbance in high and low latitude but positive disturbance in East-Asia also has been found.The results mentioned above are important for studying the characteristics of low latitude ionosphere and are significant to develop an ionospheric prediction model.