A comparison and analysis of the S4 index,C/N and ROTI over Sanya
海南三亚地区S4指数与C/N、ROTI的比较分析

Using the data received by GPS scintillation/TEC receiver at Sanya station in Ha inan province during August, 2004-July, 2005, we made some comparison and analyses of the S4 (the amplitude scintillation index), C/N (Carrier to Noise) a nd 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.