Observations of Ionospheric Irregularity Zonal Velocity in Hainan

To investigate the drift velocity of the equatorial ionospheric irregularity in low latitude of China, three single-frequency GPS receivers at Hainan (19.3ºN, 109.1ºE) were operated under the corporation of CSSAR, China and NICT, Japan. Distances between the receivers were 91 m and 104 m respectively. The GPS receivers sampled GPS signal intensity at a rate of 20 Hz. Drift velocities of irregularities were measured using cross-correlation analysis with the time series of the GPS signal intensity observed from March to November of 2007. The results indicate that the ionospheric scintillation mainly occurrs in spring and autumn. The zonal drift velocity is mainly eastward at night. It varis from 50 m/s to 150 m/s, and decreases with time. During the generation phase of plasma bubbles, the drift velocity is relatively scattered, which could be related to the random fluctuations of the plasma irregularities. And at the beginning of the scintillation, the plasma has a large vertical velocity, which can also cause the uncertainty of the zonal drift velocity. The characteristic of the drift velocity is consistent with the observational results in other stations at low latitude region.