Analysis of Correlation Between Roti and S4 Using Gagan Data

Abstract

As ionosphere is one of the most prominent sources of error, ionospheric TEC and scintillation studies are necessary for improving the performance of a navigation system. In this paper, the behavior of the correlation coefficient (ρ) between Rate of TEC Index (ROTI) and amplitude scintillation index (S 4 ) over low latitude station Hyderabad (Latitude: 17.44 • (deg.) N, Longitude: 78.74 • (deg.) E) for different seasons is analyzed. Also, the analysis is extended for nearly same longitude stations like Trivandrum, Bangalore, Bhopal, Delhi, and Shimla for the higher values of total K p index for 60 days (most disturbed 5 days per month). For Trivandrum (lowest latitude station), it is observed that both S 4 and ROTI are high as compared to Bangalore, Bhopal, Delhi, and Shimla. It is found that there is a good correlation between the temporal variations of ROTI with S 4 after post sunset hours. The confidence intervals for computed correlation coefficients at 95% confidence level are also given.

Signatures of Equatorial Plasma Bubbles and Ionospheric Scintillations from Magnetometer and GNSS Observations in the Indian Longitudes during the Space Weather Events of Early September 2017

“…There are several studies presenting scintillation occurrence characteristics with the help of ROTI in the equatorial, low-latitude, and sub-auroral regions, confirming that ROTI can be taken as a parametric index to identify the spatiotemporal variation of scintillations [33,[35][36][37][38]. The ROTI observations from 21 reference stations in China show its consistent relation with scintillation characteristics [39].…”

“…The seasonal correlation studies between the ROTI and S4 at a low latitude station (Hyderabad) demonstrate a maximum correlation of 0.95, even during the disturbed days [1]. From the occurrence probability studies, it is observed that in most cases the log-normal distribution of S4 fits well in the overall range of ROTI [38]. The time series analysis of ROTI demonstrates that a value greater than 0.5 can be considered as a threshold for identifying the presence of ionospheric irregularities [41].…”