ROTI and scintillation index correlation under quiet and disturbed periods over an Indian low latitude station, Waltair.

The variation of correlation between ROTI and S 4 index is examined by using GPS L1 and L5 signals over an Indian low latitude station, Waltair (17.73° N, 83.37° E) during the period from 2015 to 2017. The effect of geomagnetic storms on the correlation between ROTI and S 4 index is the main focus of the present study. The influence of satellite elevation angle and signal frequency on the correlation between ROTI and S 4 index is also investigated during different seasons and geomagnetic conditions. The correlation is found to vary between 0.28 and 0.63 for elevation angles above 30⁰ and between 0.56 and 0.87 for the elevation angles above 50⁰. The correlation coefficient values are decreasing with solar activity from 2015 to 2017 during quiet and disturbed geomagnetic periods. From the analysis on the seasonal correlation between ROTI and S 4 index, it is found that solar activity dependent seasonal correlation is observed for both GPS L1 and L5 signals over lower elevation angle 30⁰. The correlation between ROTI and S 4 index is increasing over higher elevation angles and for lower signal frequency. [ABSTRACT FROM AUTHOR]