Solar Activity Variations of the Ionospheric Total Electron Content Measured from GPS-TEC Data over Nepal

Abstract:

Global Positioning System (GPS) derived Total Electron Content (TEC) has been used to a wide extent to study the ionospheric variability. This measurement technique provides opportunity of investigating ionospheric perturbation from above and below the ionospheric layer and long term physical phenomenon. In this study, we found out the periodicity in the GPS-TEC measurements and investigated how the space weather activity affects the ionospheric perturbation. Vertical Total Electron Content (VTEC) derived from CHLM (28.20°N, 85.31°E) from station Nepal during the years of 2007 to 2017 has been used for the detail analysis. Solar and magnetic storms have been extracted from NASA’s OMNIWEB information explorer. Wavelet transform, wavelet power spectrum, wavelet coherence, and cross‐wavelet spectrum have been computed for day by day averages of selected ionospheric, space weather parameters from January 2007 to June 2017. Our consequences exhibit that the full-size GPS-TEC periods show up all through solar cycle 24 which are the annual oscillation, semiannual oscillation, 356‐day, 178‐day, respectively. We observed that the annual oscillation corresponds to variability in solar flux (10.7 cm) and solar Lyman‐α (Ly‐α) flux and the semiannual oscillation to variability in space weather‐related parameters geomagnetic activity variation at some point of the declining section of the photo voltaic cycle. Our outcomes are vital considering they beef up our perception of the Earth's ionospheric location response to solar forcing.