Global Ionospheric Response to Disturbances during Multistep Magnetic Storm on November 4–5, 2023

Abstract

The ionosphere, as a medium for radio wave propagation, remains highly sensitive to disturbances in geospace and largely governs the accuracy and reliability of communication, navigation, and radar systems. The most powerful drivers of disturbances in the Earth–atmosphere–ionosphere–magnetosphere (EAIM) and Sun–interplanetary medium–magnetosphere–ionosphere–atmosphere–Earth (SIMMIAE) systems are coronal mass ejections. These events restructure the coupling strength and interaction dynamics across the coupled system, generating spatiotemporal ionospheric disturbances that degrade the performance of satellite- and ground-based technologies. This study addresses the need to better understand both global and local ionospheric responses to intense, nonstationary energy inputs. We investigate ionospheric disturbances during a unique multistage magnetic storm by analyzing maps of the rate of total electron content index (ROTI) and the temporal evolution of global electron content (GEC). We identify three consecutive GEC maxima: approximately 2.20 GECU on November 4 at 22:00 UTC, followed by 2.22–2.25 GECU during the second half of November 5, as well as a deep minimum of 1.63 GECU on November 6. The resulting ionospheric plasma “saturation–depletion” cycle had an amplitude of 0.62 GECU. We observe the highest ROTI values (3.8–4.3 TECU/min) in the polar region (60°–75° N) at 04:00 UTC on November 4, while the strongest equatorial enhancement (3.6 TECU/min) occurred at 00:00 UTC the same day over South America. Strong disturbances (ROTI ≥ 0.9 TECU/min) expanded to geomagnetic latitudes up to ±40° between 18:00 UTC on November 5 and 06:00 UTC on November 6, coinciding with a sharp decline in GEC and a peak in the Akasofu parameter (ε_A ≈ 6.6 TJ/s). During the second day of the storm main phase, electrodynamic processes, including SAPS and substorms, dominated and produced a pronounced anticorrelation between reduced GEC values and enhanced ROTI activity. ROTI ≥ 1 TECU/min disturbances persisted for approximately 1 day after the D_st index recovered from –50 to –20 nT.