The occurrences of spread F and GPS phase fluctuations as well as Medium-Scale Traveling Ionospheric Disturbances over Wuhan

In this study, we analyzed the data from the digisonde and the GPS receiver at Wuhan, China (30.5°N, 114.4°E) to study spread F, GPS phase fluctuations, and Medium-Scale Traveling Ionospheric Disturbances (MSTIDs) at nighttime in 2000. The variations of seasonal and nighttime occurrence rate and the one-to-one correspondences of these phenomena were examined. The results show that all phenomena are highly active in summer, which confirms that irregularities over Wuhan mainly relate to MSTIDs. Moreover, none of large GPS phase fluctuations event had occurred during observations, which indicates that the strength of irregularities related to MSTIDs are weaker than that of equatorial plasma bubbles. Besides, the frequency spread F occurs first at nighttime which implies that disturbances start at the altitude near the F-region peak. Finally, the results of one-to-one correspondences implies that smaller scale irregularities which are observed as spread F or GPS phase fluctuations may only appear in some phase of MSTIDs.