A comparison and analysis of the S4 index, ON and ROTI over Sanya

Using the data received by GPS scintillation/TEC receiver at Sanya station in Hainan province during August, 2004 July, 2005, we made some comparison and analyses of the S-4 (the amplitude scintillation index), C/N (Carrier to Noise) and ROTI (the standard deviation of the change rate of TEC). We also analyzed the scintillation on 7 November 2004 in detail. From the comparison and analysis, we concluded as follows: (1) the scintillation strength of one year has a semiyearly periods, the maximum scintillation strength of one year appears in spring and autumn; (2) the S4 and C/N have a good negative correlation; (3) ROTI can be regarded as an indicator of the present of scintillation causing small-scale ionospheric irregularities.