Ionospheric climatology at Africa EIA trough stations during descending phase of sunspot cycle 22

Quantitative Characteristics of Equatorial Ionization Gradient Above 150 km at Low Solar Activity

“…This same observation is evident in this work. These characteristics of the postnoon N m F 2 peak magnitude decreasing with increasing solar activity is linked to faster increase in the recombination efficiency relative to the plasmaspheric flux increase (Adebesin, Rabiu, Bolaji, et al, ; Mikhailov et al, ). Higher N m F 2 peak magnitudes observed in equinox in comparison to solstices, especially during the postnoon peak periods, are ascribed to the intensity and duration of solar radiation incident on the Earth's surface.…”

“…This solar intensity empowered the F 2 layer to reach dynamic equilibrium around the local noon and in association with the vertical E x B drift causes plasma to drift up and away from the equator. This drifting is then the causative factor for the high daytime plasma depletion around local noon (which was observed between 10 and 11 LT in Figure 1a except for June solstice; see Adebesin, Rabiu, Bolaji, et al, 2018). After the noontime, at which time the solar radiation must have decreased, the E × B drift persist and initiates reduction.…”

“…They reported an extremely different morphology in the simultaneous observations of the EIA crests in both hemispheres of the Africa‐Middle East sector in comparison with the report obtained from the Asian sector. More recently, Adebesin, Rabiu, Bolaji, et al (), using ionosonde data, investigated the ionospheric climatology at three EIA region stations (Ouagadougou [12.42°N, 358.6°E], Dakar [14.7°N, 342.6°E], and Korhogo [9.51°N, 354.4°E]) in the African sector during the descending phase of solar cycle 22. They reported that the zonal electric field/height profile ( Ey/h'F ) relationship and that of the electric field/peak electron density ( Ey/N m F 2 ) revealed a more active zonal electric field in the h'F lifting and N m F 2 suppression.…”

Pattern of Ionization Gradient, Solar Quiet Magnetic Element, and F2‐Layer Bottomside Thickness Parameter at African Equatorial Location

“…The resulting eastward electric field generated from the action of the E-region dynamo are then mapped onto the F region heights (altitudes) along the equipotential magnetic field lines (Bello et al, 2017), and consequently resulting in the change of vertical ionization gradient profile, through the action of the E × B that was generated. Adebesin, Rabiu, Bolaji, et al (2018) had earlier submitted that the zonal electric field, and hence, the E × B drift is more active in the lifting of the ionospheric F region height profile, and a subsequent suppression of electron density distribution at equatorial locations. It is therefore not Figures 2a and 2b depict the monthly hourly average values of Sq field strength and B 0 , respectively.…”

“…The electrodynamics of the electron density, especially in the ionospheric F region, had been widely studied. Despite this, it is still attracting more attention because of its usefulness in a variety of scientific ways, including specification of time delay correction models of radio waves passing through the Earth's ionosphere, description of ionospheric variability and dynamics, and the depiction of empirical models in the ionospheric regions (Adebesin, Rabiu, Bolaji, et al, ; Adebesin, Rabiu, Obrou, & Adeniyi, ; Adebiyi et al, ; Adeniyi, Adebesin, et al, ; Danilov & Konstantinova, ; Mikhailov & Perrone, ; Perna & Pezzopane, ). In the equatorial and low‐latitude regions, electron density distribution is majorly governed by a number of mechanisms like the equatorial plasma fountain effect, electrodynamic drift, and equatorial electrojet current, which are triggered, either independently or jointly, by solar ionizing variation, geomagnetic activity, penetration of magnetospheric electric fields, and the action of neutral atmosphere, among others (Rishbeth & Mendillo, ).…”