Papers by Eugene O . Onori
Journal of applied science and environmental management, May 24, 2024
Ionospheric modelling is a major approach to predicting the behavior of the ionosphere particular... more Ionospheric modelling is a major approach to predicting the behavior of the ionosphere particularly in regions where Global Positioning Systems (GPS) are not readily available. Hence, the objective of this paper is to measure and compare Total Electron Content (TEC) for Assessment of Ionospheric Models during April 7, 2000 Geomagnetic Storms. Measured Total Electron Content (TEC) from experimental records (April 5 -9, 2000) were compared with those predicted by the improved versions of the International Reference Ionosphere (IRI-2012 and IRI-Plas2015) and the NeQuick models. The mean values of TEC in five days of the months were plotted against the hours of the same day and the root mean square error of the models which shows their deviations from the GPS data were used to observe the diurnal variations in TEC and the performances of the ionospheric models respectively. The data obtained confirmed that TEC has their highest values during the midnight period and lowest values during the sunset period at the Australian stations and we also confirmed that European stations had their highest TEC values during the daytime and their lowest values during the night time. We affirmed that the North American station in USA had its highest TEC values during the night time and lowest values during day time. The Asian station had its highest TEC values during the day time and lowest values during the midnight period. However, NeQuick, IRIPlas2015, and NeQ-IRI produced better estimate of TEC than the IRI-2001 and IRI-2001COR at all locations during the phases of the geomagnetic storm.
International journal of Geomatics and Geosciences, 2012
2D resistivity imaging and vertical electrical sounding (VES) surveys were integrated in the stud... more 2D resistivity imaging and vertical electrical sounding (VES) surveys were integrated in the study of the investigation of the level of groundwater contamination at lie -Epo dumpsite in Agbado Oke-Odo Local Council Development Area (LCDA), Lagos State, Southwestern, Nigeria. A total of nine vertical electrical soundings and four 2D electrical imaging using Wenner configurations was used for the study. Out of these, six YES and three 2D electrical imaging were carried out on the dumpsite while three YES and one 2D imaging were carried out in a school 100m away from the dumpsite in order to serve as control. The result of interpretation of both data suggests that the study area is underlain by sand and clay formations. Results of the resistivity Imaging delineated the contaminant plume as low resistivity zones (0.5 -48.om). This was also correlated with the YES values of 0.1 to 31.6.om which indicate contaminant plume. This was observed to have infiltrated to a depth of about 50m which poses serious health risks to the inhabitants of that area.
Asian Journal of Research and Reviews in Physics, Mar 16, 2020
Geophysical and physiochemical investigations were carried out along Lagos-Badagry Expressway, So... more Geophysical and physiochemical investigations were carried out along Lagos-Badagry Expressway, Southwest, Nigeria on three locations dominated by highway runoff, with a view to monitoring the effect of highway runoff on nearby groundwater. The locations were: Iyana Isashi, Iyana Era and Agbara. An overview of the subsurface resistivity distribution was achieved employing Vertical Electrical Sounding (VES) using Schlumberger array and Two-dimensional (2D) resistivity imaging (Wenner array). The ABEM Terrameter SAS 1000 was used for both VES and 2D resistivity surveys and the data were analysed using IPI2win and RES2DINV, respectively. The VES results showed up to four geoelectric layers consisting of sand, clayey sand, clay and sandy soils. The resistivity at Agbara was found varying from 3.52 Ωm-11 Ωm. This low resistivity value showed a high level of infiltration of highway runoff into the subsurface, thereby causing contamination of the groundwater. Iyana Isashi and Iyana Era have a relatively moderate resistivity Original Research Article
Advances in Environmental and Engineering Research
Ultraviolet (UV) and X-ray radiation are the primary causes of ionization that produce electron d... more 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 correlat...
Journal of Atmospheric and Solar-Terrestrial Physics, 2013
The variability, VR, of critical frequency of E-layer, foE, and ionospheric propagation factor, M... more The variability, VR, of critical frequency of E-layer, foE, and ionospheric propagation factor, M(3000)F2 at Ibadan (7.41N, 3.91E, 61S dip) is investigated for local time, seasonal and solar cycle variations. Latitudinal influence of these characteristics is sought by comparison with foE VR and M(3000)F2 VR of Slough (51.51N, 359.41E, 66.51N dip) in the European sector, and Singapore (1.31N,103.81E, 17.61S dip) in the Asian sector. While the pattern of foE VR is similar to those of other F2 characteristics with characteristic peaks around dawn and dusk, M(3000)F2 VR shows no clear diurnal trend. A lower bound of foE VR is usually 3% while the maximum VR ranges between 8% and13% at postsunrise and pre-sunset hours at all the epochs, M(3000)F2 VR is however lower during MSA (about 9%) than during LSA and HSA when it is 4% to about 12-14%. Generally, daytime M(3000)F2 VR is greater than that of foE VR by between 5% and 10%. Furthermore, no latitudinal difference is observed in both characteristics during both HSA and MSA. While nighttime M(3000)F2 VR is about half that of nighttime foF2 VR (the critical frequency of F2-layer) VR, daytime VR of both characteristics are about equal during the three epochs at Ibadan. For Slough, nighttime M(3000)F2 VR and nighttime foF2 VR as well as the daytime VR of both characteristics are about equal. This difference is most likely due to latitudinal effect.
Radio Science, 2013
Diurnal, seasonal, and solar cycle effects of the variability (VR) of the critical frequency of s... more Diurnal, seasonal, and solar cycle effects of the variability (VR) of the critical frequency of sporadic E layer (foEsq) are investigated at Ibadan (7.4°N, 3.9°E, 6°S dip) in the African sector during high solar activity (HSA) year of 1958 (Rz = 181), moderate solar activity (MSA) year of 1973 (Rz = 30), and low solar activity (LSA) year of 1965 (Rz = 17). The diurnal variation of foEsq VR is characterized by post‐midnight (32%–78%) and pre‐midnight (20%–84%) peaks during high solar activity (HSA), the only epoch of the three showing these peaks and a diurnal trend. While the daytime foEsq VRs of the three epochs show no seasonal trend, pre‐midnight and post‐midnight, the foEsq VRs during HSA and LSA show seasonal trends. Similarity is observed in the curve of reciprocal of percentage occurrence of Esq and that of foEsq VR, indicating inverse variation of percentage occurrence and foEsq VR. Longitudinal influence is observed in the diurnal variation of HSA and MSA July foEsq VR of I...
Correspondence Cornelius O. Ogabi, Department of Physics, Faculty of Science, Lagos State Univers... more Correspondence Cornelius O. Ogabi, Department of Physics, Faculty of Science, Lagos State University, Nigeria. Email:[email protected] Abstract: Introduction: Chaos synchronization and control in dynamical systems are essential applications of chaos theory. Chaos control is sometimes needed to refine the behavior of a chaotic model and to remove unexpected performance of power electronics. Synchronization of chaos also has useful applications to biological, chemical, physical systems and secure communications. Lyapunov exponents is one of a number of effective ways to describe chaotic properties of non-linear systems. If one of the Lyapunov exponents is greater than zero, the system is chaotic, and if at least two of the Lyapunov exponents are positive, the system is hyper-chaotic. The greater the number of positive Lyapunov exponents, the higher the degree of instability in the system. The Eulers’ equation of the rigid body has many physical applications, thus, the need to fur...
Correspondence Eugene O. Onori, Department of Physics, Faculty of Science, Lagos State University... more Correspondence Eugene O. Onori, Department of Physics, Faculty of Science, Lagos State University, Nigeria. Email:[email protected] Abstract: Introduction: The ionosphere displays a wide range of variations ranging from diurnal, seasonal, annual and solar cycle variation. In this paper we present a study of the comparison of diurnal, seasonal and semiannual variation of the variability (VR) of the critical frequency of the F2 layer (foF2) over Ilorin (Lat. 8.47oN, 4.6oE, dip 4.1oS) in the African sector,Jicamarca (Lat. 11.9oS, Long.76.8oW, dip 1oN) in the American sector and Okinawa (26.3oN, 127.8oE, dip 36.8oN) in the Asian sector during solar minimum period. These stations lie within the equatorial anomaly region of the ionosphere. Aims: To compare the diurnal, seasonal and semi-annual variation of the variability (VR) of the critical frequency of the F2 layer (foF2) over Ilorin in the African sector, Jicamarca in the American sector and Okinawa in the Asian sector during sola...
This paper reviews the variability of equatorial/low latitude F2 characteristics with emphasis on... more This paper reviews the variability of equatorial/low latitude F2 characteristics with emphasis on the most general results reported by authors. On a general note, diurnal variation of ionospheric F2 layer characteristics coefficient of variability (CV) is characterised by post- and pre-midnight peaks at all seasons, epochs and longitude. The post-midnight peak is greater than pre-midnight peak for all the characteristics considered except h’F2 CV during high solar activity (HSA) possibly due to occurrence of post-sunset pre-reversal enhancement (PRE) in height of reflection prominent during HSA. NmF2 CV is greater than CV of MUF and h’F2. MUF CV and foF2 CV are of the same order of magnitude. While seasonal trend is little or nil in daytime CV of F2 layer characteristics, nighttime CV is greater in general at the equinoxes and June Solstice. Nighttime F2 layer characteristics CV are found to decrease with increasing sunspot. This is not the case with daytime CV. Except for h’F2 CV, ...
2-D resistivity inversion survey technique of electrical resistivity method was undertaken at Lag... more 2-D resistivity inversion survey technique of electrical resistivity method was undertaken at Lagos State University (LASU) Foundation School, along Topo-Ascon road in Badagry Local Government Area of Lagos State with a view to mapping the subsurface characterization for borehole development. Dipole-dipole configuration covering the entire area was conducted using the ABEM Terrameter SAS 1000 and inter-electrode spacing of 10m, 20m, 30m and 40m were used in the traverse. The data were processed by creating a pseudo-section of the apparent resistivity values using DIIPRO software. Computer iterations were then carried out and twodimensional (2-D) resistivity contour maps were created. Four different types of soil formations were observed from the beginning to the end of the traverse but to a depth of about 2.3m while a uniform layer of clayey sand is shown on the traverse from a depth of about 2.3m to 5.0m.The areas that have favourable resistivity with appreciable thickness are sand...
Advances in Space Research
JOURNAL OF RESEARCH AND REVIEW IN SCIENCE
We present Euler’s Equation of Rigid Body, its control and synchronization using active control a... more We present Euler’s Equation of Rigid Body, its control and synchronization using active control and recursive backstepping methods. Based on Lyapunov stability theory, control laws are derived to synchronize the chaotic system and also to control to a steady state as well as track to a desired function via recursive backstepping methods. Numerical simulation are shown to verify the results.
JOURNAL OF RESEARCH AND REVIEW IN SCIENCE
Introduction: The ionosphere owes its origin primarily to ultraviolet radiation from the Sun. The... more Introduction: The ionosphere owes its origin primarily to ultraviolet radiation from the Sun. The ionosphere is an essential part of the Earth’s upper atmosphere. It is ionized by solar radiation and influences transionospheric radio wave propagation. Maximum electron density of the F2- layer (NmF2) is an important parameter for studying the ionosphere. The ionospheric F2-region maximum electron density (NmF2) depends strongly on solar activity, it also suffers temporal and spatial variations. Aim: The aim of this paper is to investigate the response of NmF2 to solar activity during high solar activity (HSA), moderate solar activity (MSA) and low solar activity (LSA) years using correlation analysis. Materials and Methods: The data used in this work are the hourly NmF2 values derived from foF2 data observed at Jicamarca (Lat.11.9 oS, Long.76.8 oW) and Puerto Rico (Lat.18.5 oN, Long.67.2 oW) during high solar activity HSA (2002), moderate solar activity MSA (2011) and low solar activ...
Annales Geophysicae
The ionosphere is the major error source for the signals of global positioning system (GPS) satel... more The ionosphere is the major error source for the signals of global positioning system (GPS) satellites. In the analysis of GPS measurements, ionospheric error is assumed to be somewhat of a nuisance. The error induced by the ionosphere is proportional to the number of electrons along the line of sight (LOS) from the satellite to receiver and can be determined in order to study the diurnal, seasonal, solar cycle and spatial variations in the ionosphere during quiet and disturbed conditions. In this study, we characterize the diurnal, seasonal and solar cycle variation in observed total electron content (OBS-TEC) and compare the results with the International Reference Ionosphere (IRI-2016) model. We obtained TEC from a dual-frequency GPS receiver located at Birnin Kebbi Federal Polytechnic (BKFP) in northern Nigeria (geographic location: 12.64 • N, 4.22 • E; 2.68 • N dip) for the period 2011-2014. We observed differences between the diurnal variation in OBS-TEC and the IRI-2016 model for all hours of the day except during the post-midnight hours. Slight post-noon peaks in the daytime maximum and postsunset decrease and enhancement are observed in the diurnal variation in OBS-TEC during the equinoxes. On a seasonal scale, we observed that OBS-TEC values were higher in the equinoxes than the solstices only in 2012. However, in 2011, the September equinox and December solstice recorded a higher magnitude, followed by the March equinox, and the magnitude was lowest in the June solstice. In 2013, the December solstice magnitude was highest, followed by the equinoxes, and it was lowest in the June solstice. In 2014, the March equinox and December solstice magnitudes were higher than the September equinox and June solstice magnitude. The June solstice consistently recorded the lowest values for all the years. OBS-TEC is found to increase from 2011 to 2014, thus revealing solar cycle dependence.
Annales Geophysicae Discussions
Total Electron Content (TEC) is an important ionospheric parameter used to monitor possible space... more Total Electron Content (TEC) is an important ionospheric parameter used to monitor possible space weather impacts on satellite to ground communication and satellite navigation system. TEC is modified in the ionosphere by changing solar Extreme UltraViolet (EUV) radiation, geomagnetic storms, and the atmospheric waves that propagate up from the lower atmosphere. Therefore, TEC depends on local time, latitude, longitude, season, geomagnetic conditions, solar cycle activity, and condition of the troposphere. A dual frequency GPS receiver located at an equatorial station, Birnin-Kebbi in Northern Nigeria (geographic location: 12.64°N; 4.22°E), has been used to investigate variation of TEC during the period of 2011 to 2014. We investigate the diurnal, seasonal and solar cycle dependence of observed (OBS) TEC and comparison with latest version of International Reference Ionosphere (IRI-2016) model. On a general note, diurnal variation reveals discrepancies between OBS-TEC and IRI-2016 model for all hours of the day except during the post-midnight hours. Slight post-noon peaks in the daytime maximum and post-sunset decrease and enhancement are observed in the diurnal variation of OBS-TEC of some months. On a seasonal scale, we observed that OBS-TEC values were higher in the
Geophysical Monograph Series, 2016
pelagiaresearchlibrary.com
2-D resistivity inversion survey technique of electrical resistivity method was undertaken at Lag... more 2-D resistivity inversion survey technique of electrical resistivity method was undertaken at Lagos State University (LASU) Foundation School, along Topo-Ascon road in Badagry Local Government Area of Lagos State with a view to mapping the subsurface characterization for borehole development. Dipole-dipole configuration covering the entire area was conducted using the ABEM Terrameter SAS 1000 and inter-electrode spacing of 10m, 20m, 30m and 40m were used in the traverse. The data were processed by creating a pseudo-section of the apparent resistivity values using DIIPRO software. Computer iterations were then carried out and twodimensional (2-D) resistivity contour maps were created. Four different types of soil formations were observed from the beginning to the end of the traverse but to a depth of about 2.3m while a uniform layer of clayey sand is shown on the traverse from a depth of about 2.3m to 5.0m.The areas that have favourable resistivity with appreciable thickness are sand formations.
Annales Geophysicae Discussions, Aug 24, 2018
Satellite radio signals are affected by the presence of electrons in the earth's upper atmosphere... more Satellite radio signals are affected by the presence of electrons in the earth's upper atmosphere (ionosphere). The more electrons in the path of the satellite radio signals, the more the impact on the accuracy of satellite navigation systems such as the Global Positioning System (GPS)/ Global Navigation Satellite System (GNSS) and GLONASS. These electrons introduce several meters of error in position calculation. Total Electron Content (TEC) is used to monitor possible space weather impacts on satellite to ground communication and satellite navigation. TEC is modified in the ionosphere by changing solar Extreme UltraViolet (EUV) radiation, geomagnetic storms, and the atmospheric waves that propagate up from the lower atmosphere. Therefore, TEC depends on local time, latitude, longitude, season, geomagnetic conditions, solar cycle activity, and condition of the troposphere.A dual frequency GPS receiver located at an equatorial station, Birnin-Kebbiin Northern Nigeria (geographic location:12.64°N; 4.22°E), has been used to investigate variation of TEC during the period of 2011 to 2014. We investigate the diurnal,
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Papers by Eugene O . Onori