Date of Award

31-8-2024

Document Type

Thesis

School

School of Electrical & Electroncis Engineering

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr.James Baskardas

Keywords

Radio Remote Sensing, Ionospheric TEC, Solar Eclipse, Equinoxes, Solstices, Empirical models, ML models, MSTID, Es-layer

Abstract

A Global Positioning System (GPS) station for ionosphere studies was established during December 2019 in Thanjavur (Geographic 10.72◦ E, 79.01◦ N, Geomagnetic 2.91◦ N, 152.22◦ E). The study involved analysing Total Electron Content (TEC) data and correcting biases to estimate Slant Total Electron Content (STEC). STEC was then converted to Vertical Total Electron Content (VTEC), useful for space weather, navigation, surveying, and environmental monitoring.

During the course of our study, this Thanjavur station witnessed a Annular Solar eclipse of Dec-26, 2019. The Solar eclipses can impact ionospheric conditions, causing VTEC depletion. This study shows how the near-earth environment changes during the solar eclipse. The empirical model is helpful for the VTEC variations. The climate models such as NeQuick2 and International Reference Ionosphere for Plasma sphere (IRI-Plas) models captured seasonal variations effectively. The study assessed climate models performance at this equatorial location, with NeQuick2 having a low Root Mean Square Error (RMSE) of 2 TECU, making it a potential choice. Machine Learning (ML) models are applied for filling the missing data.

A Bi-directional Long Short Term Model (Bi-LSTM) model significantly outperformed conventional Long Short Term Model (LSTM), reducing Mean Absolute Error (MAE) by 28%, Mean Square Error (MSE) by 48%, and RMSE by 24%. It successfully predicted VTEC during equinox and solstice periods with low errors and a good fit. There is a proposal that aimed to enhance spoofing detection in navigation systems by using ionospheric signature like STEC,

Amplitude (S4), and phase ( σφ) scintillation, increasing reliability and security for future civilian navigation systems, especially in vehicles. In summary, this research contributes valuable insights into VTEC prediction during quiet geomagnetic condition, equinox, solstice and the potential use of ionospheric signature to enhance spoofing detection in Global Navigation Satellite System (GNSS)/GPS applications for surveying/navigation. We applied a TEC for the electro dynamical coupling between Sporadic E layer (ES) and F region of the ionosphere as a case study for the future plan to our GPS station. Our finding implies that the electro dynamical coupling between the layer and F region could play an important role in growing Medium Scale Traveling Ionosphere Disturbances (MSTID) and this coupling phenomena depends the trend of Solar activity.

Download

Share

COinS