This paper presents first observations of poleward traveling ionospheric disturbances (TIDs) during strong geomagnetic conditions over the African sector. By analyzing different data sets we have observed both positive and negative ionospheric responses during the storm period of 08–10 March 2012. Considering the African region as a whole, three longitudinal sectors were strategically selected to establish the entire regional response. On both sides of the geomagnetic equator, results show poleward shift in peak total electron content (TEC) enhancements/depletions at different times which are associated to large‐scale TIDs. The observed phenomena are linked to the global ionospheric response and electrodynamics. The understanding has been established using data from International GNSS Service receiver network, radio occultation electron density profiles, derived E×B drift measurements from magnetometer observations and regional ground‐based and satellite data. Contrary to other related studies, generated regional TEC perturbation maps were not enough to show obvious directions of the large‐scale TIDs due to insufficient data over the northern hemispheric part of the African sector. There appears to be a switch between positive and negative storm phases during the same storm period especially in the Southern Hemisphere part of the African region where “enough” data were available. However, a detailed analysis revealed that the positive storm phase corresponded to the expansion of the equatorial ionization anomaly (EIA) toward some parts of midlatitude regions (and possibly with the contribution from low‐latitude electrodynamics associated to equatorial electrojet), while the other part recorded a negative storm phase due to storm‐induced changes from the auroral origin. We have observed a simultaneous occurrence of both poleward and equatorward propagating TIDs over the African sector during the same geomagnetic storm period. Our results show that short‐lived large‐scale TIDs are possibly launched by the equatorial electrojet, while the EIA expansion contributes (through modulation) to the poleward propagation of the disturbances. Temporal variation of TEC perturbations on a storm day over the entire African sector showed the existence of large‐scale TIDs during the main and recovery phases which can travel poleward up to 20° latitude. The amplitudes of the TIDs have range ±2 total electron content unit, 1 TECU = 1016 el m−2, period of 2 h and virtual velocities of 250 ± 59–750 ± 95 m/s in midlatitude regions and up to 990 ± 65 m/s within the EIA region.

We report on the first simultaneous observations of poleward and equatorward traveling ionospheric disturbances (TIDs) during the same geomagnetic storm period on a global scale. While poleward propagating TIDs originate from the geomagnetic equator region, equatorward propagating TIDs are launched from the auroral regions. On a global scale, we use total electron content observations from the Global Navigation Satellite Systems to show that these TIDs existed over South American, African, and Asian sectors. The American and African sectors exhibited predominantly strong poleward TIDs, while the Asian sector recorded mostly equatorward TIDs which crossed the geomagnetic equator to either hemisphere on 9 March 2012. However, both poleward and equatorward TIDs are simultaneously present in all three sectors. Using a combination of ground‐based magnetometer observations and available low‐latitude radar (JULIA) data, we have established and confirmed that poleward TIDs of geomagnetic equator origin are due to ionospheric electrodynamics, specifically changes in E × B vertical drift after the storm onset.

In this article, the propagation characteristics of large‐scale traveling ionospheric disturbances (LS TIDs) are estimated during the geomagnetic storm periods of 14–16 May 2005 and 25–27 September 2011 over South Africa. One and two GPS arrays have been independently considered for the storms of 15 May 2005 and 26 September 2011, respectively. The average periods of dominant modes (≈ 2.5–3.5h) in the time series data were determined by applying wavelet analysis on both ionosonde and GPS data. The consideration of diurnal GPS total electron content (TEC) variability from receivers along three different longitude sectors showed a time shift in TEC enhancement with increasing latitude, the first indication of equatorward motion of the traveling ionospheric disturbances (TIDs). The statistical method (based on GPS radio interferometry) employed shows that these TIDs were mostly propagating nearly equatorward (for both storm periods), which is consistent with the existing literature about storm‐induced TIDs. On storm days, TID horizontal velocities have been determined in the range of ≈200–500m/s. The analysis of diurnal TEC response from different stations confirmed that the positive storm effect observed on 15 May 2005 was a result of the large‐scale TIDs of wavelength ≈4000 km. On the other hand, the estimated wavelengths of LS TIDs on 26 September 2011 were ≈2400–3400km between 10 and 17 UT. A time lag is observed between the times at which enhancements in TEC, ionosonde foF2, and hmF2 data are revealed, and this has been attributed to the passage of the TID.