Total electron content at equatorial and low-, middle- and high-latitudes in African longitude sector and its comparison with IRI-2016 and IRI-PLAS 2017 models

Ogwala, Aghogho; Somoye, E.O.; Panda, Sampad Kumar; Ogunmodimu, Olugbenga; Onori, Eugene; Sharma, Sunil Kumar; Okoh, Daniel; Oyedokun, Oluwole

doi:10.1016/j.asr.2020.07.013

Cited by 18 publications

(9 citation statements)

References 59 publications

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“…The noon bite-out phenomenon is basically a result of the fountain effect. It indicates electron depletion, resulting from the E × B drift of the ion density to the ±20° latitudes [31,[54][55][56][57]. The amount of solar radiation emitted during ME and SE is usually equal.…”

Section: Discussionmentioning

confidence: 99%

“…Deviations from the winter anomaly, which is peculiar to equatorial and low latitudes, were observed during the HSA years. Winter anomalies in middle latitude regions have been previously reported [5,10,14,20,23,24,30,31]. The occurrence of this anomaly has been attributed to the effects of neutral wind composition, temperature, electric field, and other chemical parameters, such as the O/N2 ratio.…”

Section: Seasonal Variations In Nmf2mentioning

confidence: 90%

“…The negative correlation could potentially be a result of the influence of O/N2 composition, neutral wind effects, etc. A positive correlation indicates that the NmF2 value increases with an increase in the sunspot number [18,31,43,44], and a negative correlation presents the opposite case. Annual, solar cycle and latitudinal variations are observed for the correlation coefficients.…”

Section: Correlation Between Nmf2 and The Sunspot Number Rzmentioning

confidence: 99%

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Variations in the Maximum Electron Density of the F2 Layer (NmF2) over the Middle Latitude Station of Grahamstown, South Africa, during Solar Cycle 23

Ogwala¹,

Onori²,

Ogabi³

et al. 2022

Adv Environ Eng Res

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Ultraviolet (UV) and X-ray radiation are the primary causes of ionization that produce electron density in sufficient quantities to promote the propagation of satellite radio signals in the ionosphere. The electron densities suffer from spatio-temporal variations, and this poses different degrees of threats to satellite radio signals propagating through the ionosphere. We aimed to characterize the maximum electron density of the F2 layer (NmF2) in the middle-latitude ionosphere over Grahamstown, South Africa (Geographic latitude: 33.30°S, Geographic longitude: 26.50°E; Geomagnetic Latitude: 33.92°S, Geomagnetic Longitude: 89.37°E). The mean NmF2 data for solar cycle 23 (1998–2008) were used for the studies. The data were grouped into the high solar activity (HSA: 2000–2002), moderate solar activity (MSA: 1998–1999, 2003–2005), and low solar activity (LSA: 2006–2008) years. NmF2 variations were characterized based on the diurnal, seasonal, monthly, and annual data. Also, the correlation between NmF2 and the sunspot number was investigated. Results on diurnal and seasonal variations revealed that noontime bite-out of NmF2 was observed during the June solstice every year. However, it was not observed in the other three seasons. Equinoctial asymmetry is observed to show insignificant annual and solar cycle variations. The seasonal and annual variations of NmF2 with sunspot number were linear (exception: June solstice for MSA, the year 1999; HSA, years 2000–2001). The results reveal that the correlation between NmF2 and the sunspot number was insignificant under conditions of the annual, solar cycle, and latitudinal variations (exception: MSA, the year 2005; negative correlation (0.64)).

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Section: Discussionmentioning

confidence: 99%

Section: Seasonal Variations In Nmf2mentioning

confidence: 90%

Section: Correlation Between Nmf2 and The Sunspot Number Rzmentioning

confidence: 99%

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Variations in the Maximum Electron Density of the F2 Layer (NmF2) over the Middle Latitude Station of Grahamstown, South Africa, during Solar Cycle 23

Ogwala¹,

Onori²,

Ogabi³

et al. 2022

Adv Environ Eng Res

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“…The magnitude of the ionospheric impact on communication and navigation systems are directly related to the total electron content (TEC), de ned as a measure of the quantity of electrons in a unit area along the signal transmission path from the GPS satellite to a receiver on the earth's surface (Bagiya, 2009;Bhuyan, 2007). Among the most important parameters of the ionosphere that majorly in uence GPS signal and radio-wave propagations is TEC (Bolaji et al, 2023;Moses et al, 2020) due to its direct relation to the ionospheric electron density, which is the principal cause of degradation of trans-ionospheric radiowave communications signals (Olwendo et al, 2013;Bolaji et al, 2019;Aghogho, 2020). Ionospheric TEC values vary signi cantly with respect to the solar cycle, season, local time, altitude, latitude, longitude, and geomagnetic activity (Hamzah and Homam, 2015;Yan et al, 2022), because the main source of ionization (solar UV and x-ray intensity) depends on the position of the sun in the sky at a particular location on earth and on the sun's absolute output.…”

Section: Introductionmentioning

confidence: 99%

Variability of Ionospheric Total Electron Content over some American, Asian and African Equatorial Stations

AKINYEMI,

Ikubanni,

Sanyaolu

et al. 2023

Preprint

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The Earth’s ionosphere is a highly dynamic region, which interferes with radio wave propagation in the shortwave and L-band frequency. In this study, total electron content (TEC) data derived from the International Global Navigation Satellite System (GNSS) Service (IGS) over four stations were used to investigate the diurnal, seasonal and solar activity effects on ionospheric TEC variability. The stations with their respective geomagnetic latitudes are: DGAR (-16.89o), MBAR (-10.22o), BOGT (-3.80o) and AHUP (12.23o). Analysis of the diurnal variation showed that, across all the stations for all seasons, the nighttime values (ranging between 13 and 143%) are higher than the daytime values (ranging between 7 and 60%). The nighttime values showed two peaks in the range 35–143% during the post-midnight hours and 36–74% during the post-sunset hours. The diurnal-seasonal variation does not exhibit a regular pattern in any station. At three of the four stations considered, highest TEC variability was observed during low solar activity and lowest during high solar activity, particularly during the nighttime. On the average, considering all the seasons together, minimum TEC variability (7%) was observed at MBAR during March Equinox of the year of moderate solar activity and maximum (143%) was observed at AHUP during December Solstice of the year of low solar activity.

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“…The ionosphere has different latitudinal regions which includes the high ,mid and low/equatorial regions. The equatorial/low latitude region is a distinct and most dynamic part of the Earth's ionosphere that spans the region around the Earth's equator (Ogwala et al 2021;Chakraborty et al 2020;Akala et al 2020;Sivavaraprasad et al 2020;Muella et al 2008;Dabas et al 2003;Gasperini et al 2022 ). This region is characterized by unique ionospheric features and behavior due to its proximity to the equator and the interplay of various factors including solar radiation, geomagnetic effects, and atmospheric dynamics (Mengistu et al 2019;Ghodpage et al 2018;Joshua et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Total Electron Content Variations at a Low Latitude East African Station and Its Comparison with IRI-2016, IRI-Plas2017 and NeQuick-2 Models during Solar Cycle 24

Kayode,

Okoh,

Onori

et al. 2023

Preprint

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Ionospheric modelling is one of the most crucial approaches to study the activities of the ionosphere particularly in regions where experimental data are not readily available. This research aims to study the variations of Total Electron Content (TEC) in a low latitude east African station (Addis Ababa) by comparing experimental values of TEC from the Global Positioning System (GPS) with predicted data from IRI-2016, IRI-Plas2017 and NeQuick-2 models during solar cycle 24 using Root Mean Square Error (RMSE) and Mean Absolute Error (MAE) metric analysis approach. An hourly interval profile computed on seasonal basis were used to study the behaviors of TEC. A monthly interval error profile plotted on annual basis was also used to investigate the deviations of the models from the GPS values. This study analyzed TEC data from 2011 to 2017, utilizing 84 months of available data. The results from this study showed TEC have their lowest values during the post-midnight hours (02:00UT) and highest values during the pre-noon hours (11:00UT). We also observed that Equinoxes have high value of TEC than Solstices except during the ascending and maximum phases where seasonal/winter anomalies were recorded. From our statistical analysis, MAE was observed to give error value of ~ 3 TECU (TEC units) lower than the RMSE. Also from this result, we concluded that MAE is a better statistical metric than RMSE. IRI-Plas2017 outperformed IRI-2016 and NeQuick-2 models in predicting TEC values in East Africa during solar cycle 24, with a 71.4% better performance compared to other models.

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Total electron content at equatorial and low-, middle- and high-latitudes in African longitude sector and its comparison with IRI-2016 and IRI-PLAS 2017 models

Cited by 18 publications

References 59 publications

Variations in the Maximum Electron Density of the F<sub>2</sub> Layer (NmF<sub>2</sub>) over the Middle Latitude Station of Grahamstown, South Africa, during Solar Cycle 23

Variations in the Maximum Electron Density of the F<sub>2</sub> Layer (NmF<sub>2</sub>) over the Middle Latitude Station of Grahamstown, South Africa, during Solar Cycle 23

Variability of Ionospheric Total Electron Content over some American, Asian and African Equatorial Stations

Total Electron Content Variations at a Low Latitude East African Station and Its Comparison with IRI-2016, IRI-Plas2017 and NeQuick-2 Models during Solar Cycle 24

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