Comparative analysis of nocturnal vertical plasma drift velocities inferred from ground-based ionosonde measurements of hmF2 and h′F

Adebesin, B.O.; Adeniyi, J.O.; Adimula, I. A.; Oladipo, O.A.; Olawepo, A.O.; Reinisch, B. W.

doi:10.1016/j.jastp.2014.11.007

Cited by 11 publications

(12 citation statements)

References 37 publications

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“…The validation of drift inferred using h'F at Ouagadougou with that of Ilorin inferred from hmF 2 observations is made possible because Adebesin et al . [] had established a similar pattern in the drift obtained from both h'F and hmF 2 observations at a single station at nighttime. In essence, it is not so important whether one uses h'F or hmF 2 to infer the drift at nighttime since both yield similar trend.…”

Section: Methodssupporting

confidence: 64%

“…Owing to the nonavailability of direct vertical plasma drift measurements in the African sector, most drift observations are inferred using ground‐based measurements obtained either from the height of the peak electron density of the F 2 layer, hmF 2 [e.g., Liu et al ., ; Adebesin et al ., ], the virtual height of the F layer, h ' F [e.g., Sreeja et al ., ; Adebesin et al ., ], or by employing the real height at some fixed frequencies and using the means at such selected frequencies [e.g., Abdu et al ., ]. Bittencourt and Abdu [] and Bertoni et al .…”

Section: Methodsmentioning

confidence: 99%

“…[] and Adebesin et al . [] had highlighted some physical limitations associated with the accuracy of inferred vertical plasma drifts during the daytime using h ' F . For this reason, the observations of the present work are limited to the evening/nighttime periods (16–06 LT).…”

Section: Methodsmentioning

confidence: 99%

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Nighttime morphology of vertical plasma drifts at Ouagadougou during different seasons and phases of sunspot cycles 20–22

et al. 2015

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The nighttime morphology of vertical plasma drift (Vd) inferred from ground‐based measurements of the F layer height at Ouagadougou (12.4°N, 358.6°E) in the African Equatorial Ionization Anomaly trough was investigated. The observation covers four seasons, four sunspot cycle phases, annual, and 11 year sunspot cycle (SC) variations of the SCs 20–22 spanning 1966–1998 and a first attempt of such study. The annual mean peak magnitudes of Vd during the prereversal enhancement (PRE) and minimum reversal periods exhibit the 11 year sunspot cycle evolution with the sunspot number (Rz). The PRE peak/Rz and reversal peak/Rz relationships are 98.7% and 84.8%, respectively. PRE peak in June solstice appears 1 h later than for other seasons and is attributed to a decrease in the equatorial zonal wind/conductivity gradient. The highest PRE magnitude and downward perturbation drifts near dusk appear during the equinoxes and lowest in June solstice for all cycles. There is semiannual asymmetry in the variation of Vd during all cycles of the PRE event with peaks in March and September/October. A remarkable feature is the consistent local presunrise drift enhancement for two SCs 20 and 21, which is not a regular feature of the equatorial ionosphere. The rate of inhibition of scintillation effect increases with decreasing phase of sunspot activity and maximizes during the solstices. Both the PRE and minimum reversal peak magnitudes are influenced by the phase of sunspot cycle. Ouagadougou data in this study had shown reliable drift characteristics and can be integrated into the African regional empirical drift model.

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Section: Methodssupporting

confidence: 64%

Section: Methodsmentioning

confidence: 99%

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Nighttime morphology of vertical plasma drifts at Ouagadougou during different seasons and phases of sunspot cycles 20–22

et al. 2015

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“…Vertical drifts had also been useful in the description of electron density response to solar eclipses, thus making the E x B drift an essential factor for ionospheric F2layer redistribution during eclipse period [5]. The vertical drift velocities had been widely investigated in most sectors of the world including the Peruvian/American sector [6], and Indian sector [7,8,9], with little done in the African sector [10,11,12,13,14,15].…”

Section: Introductionmentioning

confidence: 99%

“…However, works that describe both methods in a single paper are scarce, even from other sectors. [15] describes the morphology of V p obtained from each method of measurement (d(hmF2)/dt) and d(h F)/dt) using digisonde data obtained from Ilorin (Geographic 8.5 • N, 4.5 • E) in the West African region during a year of low sunspot activity. For better interpretation, the result was compared with those obtained from ISR observations (which serves as the reference drift condition) spanning the same study period.…”

Section: Introductionmentioning

confidence: 99%

Current Understanding of the Equatorial E x B Drift velocities in the African Sector: A Short Review

Adebesin

Adeniyi

Adimula

et al. 2022

J. Nig. Soc. Phys. Sci.

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A short review of the pattern and morphology of the equatorial plasma drift velocities, particularly during the evening-time Pre-reversal enhancement (PRE) period in the African region had been presented. The seasonal PRE peak values across some locations in the West-African region were considered and compared with other sectors of the world. While most plasma drift observations in the African region were calculated from ionosonde measurements, the observations from other sectors involved direct measurement from satellite and the Incoherent Scatter Radar (ISR) observations. The importance of the PRE in ionospheric electrodynamics was highlighted, the better in the use of either the virtual or real heights of the F-layer in inferring vertical drift velocities were enumerated, revealing the strengths and weakness of each method. The general observations revealed that PRE peak magnitude is commonly weaker in the African region in comparison with the American/Peruvian and Indian sectors, seasonal and solar activity dependent, and could be higher during either magnetic quiet or disturbed activity than when both magnetic activity conditions are combined. The first work to present a regional PRE model around the African equatorial ionization anomaly region (Adebesin et al model) was mentioned. The relevance of the E × B drift in quantifying the daytime equatorial electrojet (EEJ) current was also discussed.

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Ionospheric vertical plasma drift and electron density response during total solar eclipses at equatorial/low latitude

2015

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The response of the vertical plasma drift (Vz) and the electron density (NmF2) during different solar eclipses was investigated. The diurnal values of the direct scaled measurement of F2 peak height and the one derived from M(3000) F2 data, acquired over an equatorial/low‐latitude stations, have been used to determine the vertical plasma drift. The ionosphere during a solar eclipse is significantly affected by the E × B vertical drift; the large depletion of electron density at low altitudes can be transported to high altitudes through the plasma vertical drift. The loss in ionization density during the eclipse phase decreases the electron density, which was accompanied by rapid increase in hmF2. This deviation in the NmF2 during eclipse compared to control days can be related to the increase in the loss rate due to recombination, as a result of reduction in thermal energy. However, the maximum reduction in NmF2 is not synchronous with the time of maximum totality but some minutes later. The differences in the solar epochs may contribute to the observed relative changes in the ionospheric F2 region behavior during the eclipse window. Lastly, it is very difficult to separate the influence of magnetic disturbances from solar eclipse. The deviation in NmF2 is higher during magnetic disturbed days than the quiet day. The reverse is the case for hmF2 observation. However, the NmF2 variation increases with an increase in solar activity.

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Comparative analysis of nocturnal vertical plasma drift velocities inferred from ground-based ionosonde measurements of hmF2 and h′F

Cited by 11 publications

References 37 publications

Nighttime morphology of vertical plasma drifts at Ouagadougou during different seasons and phases of sunspot cycles 20–22

Nighttime morphology of vertical plasma drifts at Ouagadougou during different seasons and phases of sunspot cycles 20–22

Current Understanding of the Equatorial E x B Drift velocities in the African Sector: A Short Review

Ionospheric vertical plasma drift and electron density response during total solar eclipses at equatorial/low latitude

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