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 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 S_4 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.