| Author(s) and Co-Author(s) with Affiliation: Deepthi Ayyagari(North Eastern Space Application Centre, Umiam, Shillong, 793103, India.), Shyam S Kundu(North Eastern Space Application Centre, Umiam, Shillong, 793103, India) |
| Abstract: The low-latitude ionosphere over the Indian subcontinent undergoes strong spatio-temporal variability driven by quiet-time electrodynamic processes associated with the Equatorial Ionization Anomaly (EIA), as well as disturbed-time space weather events including solar flares, coronal mass ejections (CMEs), and geomagnetic storms. These dynamic perturbations modify ionosphere-thermosphere coupling, alter vertical electron density gradients, and induce rapid Total Electron Content (TEC) fluctuations, collectively degrading the performance of emerging LEO-based Positioning, Navigation and Timing (PNT) systems. While LEO-PNT is gaining global momentum, regional ionospheric specification and system-aware error mitigation frameworks for the Indian sector remain under-developed. This work addresses this gap through high-resolution characterization of ionospheric and atmospheric responses under both quiet and disturbed space weather conditions. A dense network of dual-frequency GNSS receivers is employed to generate regional Vertical TEC (VTEC) maps, capturing low-latitude ionospheric structure, EIA evolution, and storm-time TEC enhancements and depletions. To resolve critical 3-D ionospheric gradients, slant TEC measurements are further assimilated into a physics-informed tomographic inversion framework to reconstruct electron density across altitude, latitude, and longitude. Additionally, key solar-interplanetary-geomagnetic drivers, including solar flux indices, geomagnetic activity parameters, and IMF variability, are incorporated to link ionospheric disturbances with real-time geophysical forcing. This study directly supports national space weather science priorities by contributing to regional ionospheric modelling and augmentation strategies relevant to current and future Indian missions. Beyond navigation, the proposed framework strengthens broader space-weather-impacted applications such as satellite communication, RF propagation modelling, Earth observation, and digital infrastructure resilience in low-latitude regions. The performance of the developed corrections is assessed via their impact on LEO-PNT accuracy, establishing a scalable pathway for robust, real-time ionospheric augmentation in India’s space weather-sensitive technological ecosystem. |
