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Author: search.filters.author.Phothila, PrarinyaHas files: No

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    Total Electron Content Fluctuations and Their Implications for GPS Signal Delay over Thailand: Insights from Low Latitudes during the Ascending Phase of Solar Cycle 25
    (2026-05-04)
    Keokhumcheng, Thanapon
    ;
    Phothila, Prarinya
    ;
    Maichuen, Samatchaya
    ;
    Buakao, Nitipat
    ;
    Zhang, Jianfeng
    This research investigates how fluctuations in Total Electron Content (TEC) on the global positioning system (GPS) affect GPS performance in Thailand’s low latitude region during the ascending phase of solar activity 25<sup>th</sup>, utilizing data from 2023 to 2025. To capture TEC variations, five GPS monitoring stations were strategically deployed along a north-south transect across Thailand including Bangkok station, Chiang Mai station, KMITL Chumphon station, Nongbualumphu station, and Phuket station. TEC data collected from these stations were analyzed using statistical techniques with comparisons to IGS and IRI models to explore ionospheric dynamics and solar activity throughout the ascending phase of the cycle years, influencing TEC values and the time delay in the navigation system. The research reveals how solar-induced ionospheric changes influence TEC levels and cause time delays in GPS signals, which are critical factors for satellite navigation accuracy. These insights pave the way for enhancing GPS reliability and efficiency in low latitude regions, contributing to the development of more robust global navigation systems.
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    GNSS Receiver Bias Model for Near Real Time TEC Monitoring at Low Latitude, Thailand
    (2026-01-01)
    Kenpankho, Prasert
    ;
    Maichuen, Samatchaya
    ;
    Phothila, Prarinya
    ;
    Zhang, Jianfeng
    ;
    Keokhumcheng, Thanapon
    This research proposes and investigates GNSS receiver bias modeling for near real time total electron content (TEC) monitoring across 16 multi-frequency GNSS stations in low latitude, Thailand, from 2022-2024. By applying a refined methodology based on Kenpankho et al. (2021) and integrating IONOLAB-BIAS for single station bias estimation, the research corrects for satellite and receiver inter-frequency biases to enhance TEC accuracy. Results show a consistent upward trend in TEC values, reflecting increased latitudes, seasonal ionospheric activity, and geomagnetic storms. Comparative analysis with the IRI 2020 model using correlation coefficients and RMSE reveals spatial and temporal variation, with near equatorial latitude stations showing strong alignment than upper low latitude stations. The results highlight the importance of localized GNSS-based TEC models for improving satellite positioning accuracy in equatorial regions and highlight the limitations of global models under dynamic ionospheric conditions.
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    The Study of the Rate of TEC Index over Thailand
    (2025-01-01)
    Buakao, Nitipat
    ;
    Phothila, Prarinya
    ;
    Kenpankho, Prasert
    This study examines the variations in Rate of TEC Index (ROTI) across three provinces in Thailand-Bangkok, Chiang Mai, and Chumphon-using Total Electron Content (TEC) data derived from BG2s GPS receivers during the period from January to March 2025. ROTI values were classified into three levels: high (>0.8), moderate (0.4-0.8), and low (<0.4) TEC variability. The analysis revealed that Chumphon exhibited the highest TEC variability, followed by Bangkok and Chiang Mai. In January, Bangkok recorded elevated ROTI values between 14:25 and 15:25 local time, with lower values observed from midnight to noon and after sunset. In February, ROTI values exceeding 0.8 were detected between 13:00 and 20:00, with Chumphon showing the most intense fluctuations. In March, high ROTI values occurred from 13:00 to 22:00, with Bangkok experiencing the most prolonged periods of TEC disturbance. These results underscore the spatial and temporal dynamics of ionospheric irregularities in low-latitude regions and support the effectiveness of ROTI as a diagnostic tool for monitoring space weather impacts on GNSS signals.