Toward a GIC Hazard Model for Indonesia: Analysing Latitudinal Effects of Geomagnetic Storms on the 210° Magnetic Meridian
DOI:
https://doi.org/10.17794/rgn.2026.5.10Keywords:
geomagnetic storm, equatorial electrojet (EEJ), auroral electrojet (AE), coronal mass ejection (CME), co-rotating interaction region (CIR), 210° magnetic meridianAbstract
Geomagnetically induced currents (GICs) arise during geomagnetic storms, which altering ionospheric and magnetospheric current systems from auroral to equatorial latitudes. This study examines the latitudinal response of the H-component (ΔH) during 91 storm events (56 coronal mass ejection (CME)-driven and 35 corotating interaction region (CIR)-driven) from 1992 to 1999. This study uses data from 29 observatories along the 210° magnetic meridian (MM), both storm types exhibit a distinct inverted-omega (ω) latitudinal structure, biggest around aurora, characterized by strong auroral electrojet (AE), minima near ~±50° magnetic latitude, and enhanced low-latitude disturbances linked to equatorial electrojet (EEJ) currents. CME-driven storms produce larger ΔH amplitudes and steeper gradients due to impulsive forcing and prompt penetration electric fields (PPEFs), whereas CIR-driven storms show weaker but more persistent responses influenced by disturbance dynamo electric fields (DDEFs) processes. In the Indonesian sector, at Biak and Pontianak (~9°–17° S magnetic latitude), low-latitude responses are comparable to near-equatorial observations, indicating efficient penetration of equatorial electrodynamics. Despite smaller absolute ΔH amplitudes than at auroral latitudes, these responses remain spatially coherent and significant. The transition region near ~±50° magnetic latitude and the distinct day-night asymmetry between storm types provide important constraints for GIC hazard assessment in equatorial power systems. Usually, the large ΔH in CME-driven storms is often accompanied by enhanced dB/dt. The geomagnetic storms by CME-driven can generate significant geoelectric fields even at low latitudes. The results show that Indonesia is not immune to the hazards associated with GIC. The observed systematic structure (ω) and associated geoelectric fields provide new evidence that Indonesia's regions are potential subject to substantial GIC impacts, particularly when CME-driven storms.
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Copyright (c) 2026 Setyanto Cahyo Pranoto, Anwar Santoso, Sismanto Sismanto, Eddy Hartantyo, Rhorom Priyatikanto; Nizam Ahmad; Silmie Vidiya Fani, Djohar Syamsi, Kuncoro Wisnu, Mario Batubara, Fitri Nuraeni, Siska Filawati, Muzirwan
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