Analysing impact of major solar flares on ionospheric TEC with RTISM model using IRNSS receiver, at SVNIT, Surat, India

Abstract

Indian regional navigation satellite system (IRNSS) is a navigation system developed by the Indian Space Research Organisation (ISRO), India. The IRNSS receiver granted by Space Application Centre (SAC), ISRO, Ahmedabad is installed at SVNIT, Surat, India. A solar flare is a natural event that occurs when an unpredicted flash of distended Sun's illumination is observed near its surface. The ionosphere is greatly ionised by solar radiations. Hence it is a current challenge to investigate effects of ionospheric scintillation on IRNSS signals. This study examines impact of major solar flare events like Class ‘C’ solar flare happened on 22 July 2016 and class ‘M’ solar flare occurred on 23 and 24 July 2016, on IRNSS signals with measurement of total electron content (TEC). Real-time ionospheric scintillation monitoring (RTISM) model based on empirical mode decomposition (EMD) and second-order Daubechies (db2) wavelet is used for comparing measured and denoised TEC. The RTISM model is also used for determining automatic threshold using Neyman–Pearson detector, probability of detection and probability of false alarm. It is proven with analysis that EMD is giving more sharp results as compared to db2 wavelet for determining fluctuations in TEC during the solar flare events.