The Ionospheric Dynamics of the African Sector Responding to a Severe Geomagnetic Storm; the Storm of 3–5 November 2021

Abstract

A geomagnetic storm is a disturbance on the Earth's magnetic field resulting from enhanced energy transfer from interplanetary space to the Earth's environment through the magnetosphere. The cause of geomagnetic storms is variation in the solar wind parameters, that is enhancement in solar wind speed and solar wind particles that increase solar wind pressure, and at least >3 hr sustained southward interplanetary magnetic field (IMF) on the day side magnetosphere (Gonzalez et al., 1994;Kumar & Kumar, 2019). The major solar driver of this disturbance is the coronal mass ejections (CMEs) embedded with large plasma emissions from the sun, taking several hours or days to reach the Earth's atmosphere. It should be noted that other sun's emissions like high solar wind speed from coronal holes, and corotating interaction regions also contribute to geomagnetic storms (Richardson, 2018;Richardson et al., 2006). The geomagnetic storm effects induce ionospheric disturbances characterized

3‐D Ionospheric Imaging Over the South American Region With a New TEC‐Based Ionospheric Data Assimilation System (TIDAS‐SA)

“…The SYM-H index exhibited two major negative peaks, which are −111 nT at 08:25 UT and −117 nT at 13:00 UT on 04 November, respectively. Several previous studies have reported that this geomagnetic storm triggered notable low-latitude ionospheric disturbances, especially over the South American sector (Rukundo, 2023;K. Wu et al, 2023;Zhai et al, 2022).…”

“…The SYM‐H index exhibited two major negative peaks, which are −111 nT at 08:25 UT and −117 nT at 13:00 UT on 04 November, respectively. Several previous studies have reported that this geomagnetic storm triggered notable low‐latitude ionospheric disturbances, especially over the South American sector (Rukundo, 2023; K. Wu et al., 2023; Zhai et al., 2022). This provides a good opportunity to assess our newly developed TIDAS‐SA regional data assimilation system and conduct an in‐depth analysis of the storm‐induced ionospheric perturbations.…”

Westward PPEF Plays Important Role in the Suppression of Post‐Midnight Plasma Irregularities: A Case Study of the November 2021 Geomagnetic Storm

“…On other days, a normal trend of diurnal EEJ is observed in the African sector with westward EEJ (CEJ effects) and eastward EEJ in the early morning and evening, respectively. In this context, Rukundo (2023) also studied the ionospheric dynamics of the African Sector in response to a severe geomagnetic storm of 3–4 November 2021. The African ionosphere responded to the storm with distinct features characterized by the equatorward traveling atmospheric disturbances and electric fields.…”

“…Rukundo (2023) used MIT‐based TEC to study temporal fluctuations in TEC across the African longitudinal sector. On November 3rd and 5th, separate EIA crests at approximately 15° on either side of the geomagnetic equator were observed.…”

“…During the recovery phase, the decrease in the thermospheric composition is generated by an increased N 2 density with high recombination that leads to negative storm effects. Note, the hemispherical differences from South to the North may be due to a considerably higher O/N 2 ratio in the northern than in the southern hemisphere (Rukundo, 2023). In this context, Figure 9 shows the global maps of O/N 2 ratio from GUVI TIMED during the period November 1-6, 2021.…”