Bibliography

The African equatorial ionization anomaly response to the St. Patrick’s Day storms of March 2013 and 2015

The ionosphere around the Equatorial Ionization Anomaly (EIA) region exhibits complex dynamics and responds markedly to the solar-magnetospheric energy and momentum. In this paper, the hourly total electron content (TEC) variations in response to the EIA structure in Africa to the 2013 and 2015 St. Patrick’s Day storms is investigated using data obtained from a chain of GPS receivers located in the Africa region. The TEC variations are characterized based on the convective magnetospheric dynamo fields, neutral wind circulation, and zonal electric fields. Generally, the result indicates that the TEC variations are consistent with the different directions of the interplanetary fields during the different phases of the storms. We observed reverse EIA structures in the main phase of the March 2015 storm, likely to be related to the intense PPEF and strong equatorward wind, which imposed a westward zonal electric field at the equator. A similar equatorial peak observed during the recovery phase is associated with DDEF, poleward wind and plasma convergence. Furthermore, the TEC variations also indicate hemispheric asymmetries during the storms. During the main phase of the storm, the TEC variation is more enhanced in the Northern Hemisphere in March 2013 and reverses during March 2015. We observed an equatorial peak during the SSC period in March 2013, while EIA structures are generally weak in March 2015 event. This posit that ionospheric pre-storm behaviour in the EIA region can be better understood when the IMF-Bz and E-field are not significant. The observed distinctive response avowed the peculiarity of the electrodynamics intricacy in the Africa sector.

Bolaji, Olawale; Adekoya, Bolarinwa; Adebiyi, Shola; Adebesin, Babatunde; Ikubanni, Stephen;

Published by: Astrophysics and Space Science      Published on: jan

YEAR: 2022     DOI: 10.1007/s10509-021-04022-5

TEC; EIA; DDEF; Plasma reversal; PPEF; Pre-storm

Storm time effects on latitudinal distribution of ionospheric TEC in the American and Asian-Australian sectors: August 25--26, 2018 geomagnetic storm

On the dayside of August 25–26, 2018 (main phase, MP of the storm), we unveiled the storm time effects on the latitudinal distribution of ionospheric total electron content (TEC). We used 17 and 19 Global Positioning System receivers in American and Asian-Australian sectors, respectively. Also, we employed a pair of magnetometers in each sector to unveil storm time effects on vertical E × B upward directed inferred drift velocity in the F region ionosphere. Also used is NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite airglow instrument to investigate storm time changes in neutral composition, O/N2 ratio. In this investigation, we corrected the latitudinal offset found in the works of Younas et al. (2020, https://doi.org/10.1029/2020JA027981). Interestingly, we observed that a double-humped increase (DHI) seen at a middle latitude station (MGUE, ∼22°S) after the MP on the dayside in American sector (Younas et al., 2020, https://doi.org/10.1029/2020JA027981) did straddle ∼23.58°N and ∼22°S. On August 25, 2018, storm commencement was evident in Sym-H (∼−8 nT) around 18:00 UT. It later became intensified (∼−174 nT) on August 26 around 08:00 UT. During storm s MP (after the MP), fountain effect operation was significantly enhanced (inhibited) in Asian-Australian (American) sector. Middle latitude TEC during MP got reduced in American sector (13:00 LT–15:40 LT) compared to those seen in Asian-Australian sector (13:00 LT–15:40 LT). The northern equatorial peak (∼25 TECU) seen at IHYO (14:00 LT) after MP in the American sector is higher when compared with that (∼21 TECU) seen at PPPC (11:40 LT) during MP in Asian-Australian sector.

Bolaji, O.; Fashae, J.; Adebiyi, S.; Owolabi, Charles; Adebesin, B.; Kaka, R.; Ibanga, Jewel; Abass, M.; Akinola, O.; Adekoya, B.; Younas, W.;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2021     DOI: 10.1029/2020JA029068

double-humped increase (DHI); equatorial ionization anomaly (EIA); prompt penetrating electric field (PPEF); storm time equatorward wind

Plasma transport process in the equatorial/low-latitude ionosphere

The behaviour of the equatorial/low-latitude ionosphere and the transport processes during magnetic disturbed and quiet periods of a high solar activity year, 2014, in the American sector are investigated. Parameters used include vertical drift (Vz), transport term (W), NmF2, hmF2 and scale-height (H). The F2 plasma variations followed the diurnal local solar pattern, being higher at daytime. The sunset maximum and sunrise minimum peaks of hmF2 were directly opposite to the scale height (H) pattern. The plasma distribution was basically controlled by combined actions of the electrodynamic convection/thermospheric composition, which is geomagnetic activity dependent. The annual, semi-annual and winter-anomalies of the F2 parameters were higher at the dip equator in comparison with the low-latitude. The Vz pre-reversal peak magnitude coincided with hmF2 peak and the effects are more pronounced during geomagnetic disturbed conditions. The transport term pattern was similar to that of the scale height and it is suggested as a proxy parameter for quantifying low-latitude plasma irregularities and distribution of thermospheric composition.

Adebesin, Babatunde; Adekoya, Bolarinwa; David, Timothy;

Published by: Advances in Space Research      Published on: 03/2019

YEAR: 2019     DOI: 10.1016/j.asr.2018.11.013

Response of GPS-TEC in the African equatorial region to the two recent St. Patrick s day storms

The 2015 St. Patrick’s Day storm is one of the most intense geomagnetic storm in this present solar cycle (SYM-H=-213nT). In this paper, we investigate the response of the African low

Ikubanni, SO; Adebiyi, SJ; Adebesin, BO; Dopamu, KO; Joshua, BW; Bolaji, OS; Adekoya, BJ;

Published by: International Journal of Civil Engineering and Technology      Published on:

YEAR: 2018     DOI:

Ionospheric F2 layer responses to total solar eclipses at low and mid-latitude

In this article, we presented ionospheric F2 responses to total solar eclipses on the basis of the data obtained from five (5) equatorial/low-latitude and twenty-seven (27) mid-latitude ionosonde stations, which are within the obscuration percentage of 50\textendash100\% of the path of the total solar eclipses progression. Statistically, the diurnal changes in the F2 layer peak height hmF2 and electron density NmF2, as well as the latitudinal and hemispheric dependence and the contribution of both magnetic and solar activities during the eclipse window were investigated. The estimation of the solar ionizing radiation that remains unmasked during the eclipse window was as well carried out. Plasma diffusion processes dominate the F2 region plasma, and determine the height at which the F2 peak formed at mid-latitude. The electron density decreased during the eclipse window, closely following the variation in the local solar radiation at the mid-latitude. However, at equatorial/low-latitude, the plasma distribution during total solar eclipse depends on combine effect of solar radiation and the background nighttime ionospheric irregularities mechanism. The uncertainty level of the estimated solar ionizing radiation was \<\textpm0.3 at mid-latitude and greater\textpm0.3 at equatorial/low-latitude. Their correlation ranges from (0.42\textendash0.99). The ionospheric\ F2 layer eclipse effect is latitudinal and hemispheric dependent. The effect is largest at mid-latitude and relatively small at equatorial/low-latitudes. It is more pronounced at the equator, and decreases toward the equatorial ionospheric anomaly (EIA) region. The better correlation of 0.5840 and 0.6435 between geographic latitude and\ E(t) and electron density justifies the latitudinal relationship. The increase in percentage deviation of electron density increases with latitude and delay time (∆T) in the northern hemisphere of the mid-latitude. Conversely, in the southern hemisphere the percentage deviation decreases with an increase in ∆T\ and the latitude. The influence of the combined effect of solar activity and magnetic disturbances cannot the overlooked during total solar eclipse. At the eclipse shadow, the deviation increases with decreasing magnetic disturbances and solar activity. During magnetic quiet conditions the variation in maximum NmF2/hmF2 on the eclipse day are more decrease/increase than the control day and overturned during the magnetic disturbed condition.

Adekoya, B.J.; Chukwuma, V.U.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 02/2016

YEAR: 2016     DOI: 10.1016/j.jastp.2016.01.006

Equatorial/low-latitude; Hemisphere; mid-latitude; NmF2 and hmF2; Solar ionizing radiation