Correlations between Strong Range Spread-F and GPS L-Band Scintillations Observed in Hainan in 2004

Data from the DPS-4 digisonde and the GPS L-band ionospheric scintillation monitor are employed to study the correlations between strong range spread-F （SSF） and GPS L-band scintillations observed in the ionosphere over Hainan Island, China （19.5°N, 109.1°E geogr., dip lat. 9°N） in 2004. The SSF in the ionogram is different from the general range spread-F because it extends in frequency well beyond FoF2 and makes FoF2 difficult to be determined. The observations show that the SSF phenomenon is frequently accompanied by the occurrence of GPS L-band scintillations. The SSF and GPS L-band scintillations occur frequently in the equinoctial months （March, April, September, and October）, but rarely in the winter （January, February, November, and December） and summer （May-August）; especially, occurrence variations of the SSF and GPS L-band scintillations nearly have a same trend. The SSF and scintillations may be associated with the occurrence of topside plasma bubbles and could be explained by the eneralized Rayleigh-Taylor instability.