Comparative Study of the Equatorial Plasma Bubbles using VHF Radar Images and Spatial ROTI Maps at Low-Latitude Region

Napat Tongkasem, Lin M.M. Myint, Pornchai Supnithi, Kornyanat Hozumi, Michi Nishioka

Peer Reviewed

Abstract:	Equatorial Plasma Bubbles (EPBs) depict electron density depletion region originating at the bottom side of the F layer in the ionosphere. The EPBs are often observed in the low latitude region after post-sunset period, particularly, in equinoctial months. Since EPBs have a negative impact on high-precision positioning techniques, degrading convergence time and accuracy, it is essential to study the spatial variations of EPBs during their lifetime. In this work, we develop 2-D temporal-spatial maps based on the rate of change TEC change (ROTI) index analyzed from pseudorange information in a GNSS receiver network over Thailand. The area covers the magnetic equatorial and low-latitude regions including equatorial ionosphere anomaly (EIA). Using 2-D ROTI maps (longitude vs latitude), two types of ROTI keograms (time vs latitude and time vs longitude), we analyze the spatial and temporal changes of recent EPB events. Complementing this analysis, we propose to jointly anlayze the VHF radar images at Prachomklao Chumphon VHF radar station (Lat:10.72 N, Lon: 99.37, Magn. Lat: 1.34). The radar system can scan the ionosphere from geographic latitude 0° N to 20° N and from 140 to 860 km altitude range. The results show that with the three types of data methods, characterizations, speed, velocity and occurrences of EPB are obtained.
Published in:	Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023) September 11 - 15, 2023 Hyatt Regency Denver Denver, Colorado
Pages:	3947 - 3954
Cite this article:	Tongkasem, Napat, Myint, Lin M.M., Supnithi, Pornchai, Hozumi, Kornyanat, Nishioka, Michi, "Comparative Study of the Equatorial Plasma Bubbles using VHF Radar Images and Spatial ROTI Maps at Low-Latitude Region," Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023), Denver, Colorado, September 2023, pp. 3947-3954. https://doi.org/10.33012/2023.19416
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