Longitudinal Variability of Ionospheric Scintillation Over Indonesia: Insights from GISTM-Based S4 Index Mapping and TEC Fluctuations Dyah Rahayu Martiningrum1,2*, Suhaila M Buhari1*, Prayitno Abadi2,3, Sri Ekawati2, Teguh N Pratama2
1. Dept. of Physics Universiti Teknologi Malaysia, Skudai, Johor Bahru, 81310, Malaysia
2. Research Center for Climate and Atmosphere, National Research and Innovation Agency, Bandung, Indonesia
3. School of Electrical Engineering, Telkom University, Bandung, Indonesia
Abstract
Equatorial ionospheric scintillation is frequently observed over Indonesia and may significantly affect satellite-based communication and navigation systems. This study examines the longitudinal variability of ionospheric scintillation across the Indonesian region using S4 index observations obtained from four GPS Ionospheric Scintillation and TEC Monitor (GISTM) stations located at Pontianak, Bandung, Manado, and Kupang during March 2015. Scintillation events were identified and mapped through ionospheric pierce point (IPP) projections at an altitude of 350 km. The analysis shows noticeable east-west differences in scintillation occurrence over Indonesia. Strong scintillation events (S4 > 0.5) were predominantly detected within geographic latitudes between 0 deg and 10 deg S, with the highest intensity concentrated around 5 deg S-6 deg S. Several observed events exhibited distinct regional characteristics, including cases where strong scintillation appeared simultaneously across all observation sectors, as well as events confined mainly to either the western or eastern region of Indonesia. Differences in scintillation onset time between eastern and western longitudes indicate the longitudinal development of ionospheric irregularities across the region. These results emphasize the dynamic and localized behavior of equatorial ionospheric scintillation over Indonesia and demonstrate the value of multi-station observations for regional ionospheric monitoring and future space weather studies.
