论文部分内容阅读
The GPS L-band ionospheric scintillation produced by electron density irregularity in the ionospheric E- and F-regions,is mainly a low- and high-latitude phenomenon.In this study,the statistical behavior of GPS ionospheric scintillation over a Chinese low-latitude station Sanya (18.3°N,109.6°E; dip lat: 12.8°N),including the seasonal and solar activity dependence,the onset time,and the zonal drifts of irregularities producing GPS ionospheric scintillation during the period from July 2004 to December 2012 has been investigated.The amplitude scintillation pattern,with a maximum occurrence during equinox of solar maximum,agrees with plasma bubble observations by in-situ satellites in this longitude.The drifts of irregularities estimated using two spatially separated GPS receivers over Sanya show a similar behavior during two equinoxes,slowly decreasing from 150 m/s at post sunset to 50 m/s near midnight.A significant equinoctial asymmetry of scintillation onset time is found.The initiation of scintillation during the spring equinoctial months (March-April) is on average earlier than that of autumn months (September-October) about 25 min.In addition,daytime periodic scintillation was recorded during June solstitial months of solar minimum.Possible mechanisms responsible for the occurrence characteristics of GPS scintillation over Sanya are discussed.