Samuel Ogunjo
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View article: Estimation of Surface PM2.5 Concentration from Satellite Aerosol Optical Depth Using a Constrained Observation-Based Model
Estimation of Surface PM2.5 Concentration from Satellite Aerosol Optical Depth Using a Constrained Observation-Based Model Open
Studies have established that extreme air pollution is more prevalent and is responsible for more deaths and disability-adjusted life years (DALY) in urban cities, especially in developing economies. However, the paucity of ground-based ob…
View article: Deep Learning Prediction of Inter-storm Parameters Using Transformer Convolution Network
Deep Learning Prediction of Inter-storm Parameters Using Transformer Convolution Network Open
The global impact of space weather has created interest in understanding and prediction of geomagnetic storms. Most approaches have considered the prediction of geomagnetic storms based on the time series. In this study, two characteristic…
View article: Nonlinear and multifractal behaviour of atmospheric parameters and particulate matter in South Africa
Nonlinear and multifractal behaviour of atmospheric parameters and particulate matter in South Africa Open
This study investigates the nonlinear and multifractal behavior of atmospheric parameters and particulate matter (PM10) in South Africa. We employed nonlinear techniques such as Sample Entropy, Lyapunov Exponent, and Correlation Dimension,…
View article: Long term spatial trends in West African monsoon precipitation
Long term spatial trends in West African monsoon precipitation Open
Across West Africa, rainfall is a vital weather component. Its importance in agriculture, the economy, and even governance across the region cannot be overstated due to the nature of the socio-economic vulnerabilities within this region. T…
View article: Long-term variability study of total column ozone over Nigeria using multi-sensor reanalysis measurements
Long-term variability study of total column ozone over Nigeria using multi-sensor reanalysis measurements Open
This study investigated the long-term changes in the total column ozone (TCO) over Nigeria using measurements retrieved from the ozone (O3) multi-sensor reanalysis (MSR). It assessed the spatial variability of TCO in Dobson Unit (DU), its …
View article: The effect of solar radiation modification on agroclimatic indices in Africa
The effect of solar radiation modification on agroclimatic indices in Africa Open
Africa’s agriculture, largely rain-dependent, is exceptionally vulnerable to the impacts of climate change, with projected shifts in temperature and precipitation patterns posing significant challenges for crop production, water availabili…
View article: A Bootstrapping Convolutional Neural Network Technique for Optimizing Automated Detection of Equatorial Plasma Bubbles by Optical All‐Sky Imagers
A Bootstrapping Convolutional Neural Network Technique for Optimizing Automated Detection of Equatorial Plasma Bubbles by Optical All‐Sky Imagers Open
Equatorial plasma bubbles (EPBs) disrupt satellite‐based communication and navigation systems, particularly in equatorial regions. Reliable detection and classification of EPBs from all‐sky imager (ASI) images are essential for accurate sp…
View article: Health risk assessment of heavy metals and radionuclides in waste and soil near scrap smelting industries in Ile-Ife and Ikirun, Nigeria
Health risk assessment of heavy metals and radionuclides in waste and soil near scrap smelting industries in Ile-Ife and Ikirun, Nigeria Open
The smelting plants facilitate the recycling of metal wastes as well as a secondary source for metal production. Nevertheless, the wastes from such plants may present routes of heavy metal and radionuclide contamination in the environment.…
View article: Variability in global 7Be and drivers of its distribution using multifractal detrended fluctuation analysis
Variability in global 7Be and drivers of its distribution using multifractal detrended fluctuation analysis Open
Multifractal formalism was used to examine daily 7Be activity concentrations data from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) in 21 different locations worldwide between 2010 and 2017.  The 7Be distribution acr…
View article: Projected Impact of Stratospheric Aerosol Injection on Rainfall dynamics over West Africa using ARISE Dataset.
Projected Impact of Stratospheric Aerosol Injection on Rainfall dynamics over West Africa using ARISE Dataset. Open
Agricultural production is highly dependent on rainfall dynamics (onset, cessation, length of rainy season) in the West African region, whose livelihood and economy are highly dependent on rainfed agriculture. The impact of global warming …
View article: Radiation Dosimetry and Heavy Metal Assessment of Honey in Akure, Ondo State, Nigeria
Radiation Dosimetry and Heavy Metal Assessment of Honey in Akure, Ondo State, Nigeria Open
Honey samples from the wild, apiary, and commercial outfits have been evaluated for the activity concentration of 40K, 238U, and 232Th using gamma spectrometry, and for heavy metals using Atomic Absorption Spectroscopy. The mean committed …
View article: Complexity and Nonlinear Dependence of Ionospheric Electron Content and Doppler Frequency Shifts in Propagating HF Radio Signals within Equatorial Regions
Complexity and Nonlinear Dependence of Ionospheric Electron Content and Doppler Frequency Shifts in Propagating HF Radio Signals within Equatorial Regions Open
The abundance of ions within the ionosphere makes it an important region for both long range and satellite communication systems. However, characterizing the complexity in the ionosphere within the equatorial region of Abuja, with geograph…
View article: Time series analysis of a 22-year record of 7Be, 210Pb and gross alpha activities in the Canary Islands (Spain) using Principal Component and Multifractal Detrended Fluctuation Analyses
Time series analysis of a 22-year record of 7Be, 210Pb and gross alpha activities in the Canary Islands (Spain) using Principal Component and Multifractal Detrended Fluctuation Analyses Open
The long-term variability of a 22-year dataset of 7Be, 210Pb and gross alpha concentrations in surface aerosols collected in the Canary Islands has been analysed in this study. These "time series" were collected on a weekly basis. Various …
View article: Imprints of large‐scale climate oscillations on river flow in selected Canadian river catchments
Imprints of large‐scale climate oscillations on river flow in selected Canadian river catchments Open
We investigated the impacts of six major climate oscillations on river flow at three stations within the Humber catchments (located in Ontario, ON and Newfoundland and Labrador, NL) from 1970 to 2020 using sensitivity and wavelet analyses.…
View article: Evolving Patterns in Irrational Numbers Using Waiting Times between Digits
Evolving Patterns in Irrational Numbers Using Waiting Times between Digits Open
There is an increasing interest in determining if there exist observable patterns or structures within the digits of irrational numbers. We extend this search by investigating the interval in position between two consecutive occurrences of…
View article: Leveraging satellite and reanalysis air quality data for bottom-up approach in tackling air pollution in nigeria
Leveraging satellite and reanalysis air quality data for bottom-up approach in tackling air pollution in nigeria Open
The failure of air pollution mitigation strategies at national levels can be attributed to the disconnect between policy makers and creators of this pollutants. This is not unconnected to lack of data at the smallest level of the society. …
View article: Predicting River Discharge in the Niger River Basin: A Deep Learning Approach
Predicting River Discharge in the Niger River Basin: A Deep Learning Approach Open
Across West Africa, the River Niger is a major source of freshwater. In addition, the river system also provides services such as aquaculture, transportation, and hydropower. The river network plays a critical role in the hydropolitics and…
View article: Effects of two commonly used herbicides on soil microbial activity under conservation tillage
Effects of two commonly used herbicides on soil microbial activity under conservation tillage Open
Global food sustainability and security are largely dependent on soil health and the microbial community. However, research has shown that soil health and microbial community have been incidentally affected by herbicide application during …
View article: Multidecadal trend analysis of hydrological drought along River Niger using the Streamflow Drought Index
Multidecadal trend analysis of hydrological drought along River Niger using the Streamflow Drought Index Open
Droughts affect human well‐being and the economy of countries across the world. Understanding the long‐term evolution of droughts within a particular region will help in drought mitigation and adaptation plans, thereby reducing drought imp…
View article: Spatio-temporal influence of solar activity on global air temperature
Spatio-temporal influence of solar activity on global air temperature Open
Previous studies on the impact and influence of solar activity on terrestrial weather has yielded contradictory results in literature. Present study presents, on a global scale, the correlation between surface air temperature and two solar…
View article: Exploring the suitability of narrow-bandgap compounds for thermoelectric application
Exploring the suitability of narrow-bandgap compounds for thermoelectric application Open
Different opinion exists regarding the role of bandgap size on thermoelectric variables. Motivated by the observation that the band shape can in a definite way affect thermoelectric properties, two compounds (BaSiSr and IrBiZr) have been e…
View article: The Impact of the First and Second Waves of COVID‐19 Pandemic in Nigeria
The Impact of the First and Second Waves of COVID‐19 Pandemic in Nigeria Open
In recent times, the COVID‐19 pandemic has been the subject of global concern. It has so far claimed over 5.4 million lives globally, with over 291 million cases recorded worldwide as of 5 January 2022. It is known to have different waves …
View article: Densification of air quality monitoring in Nigeria: Progress and challenges
Densification of air quality monitoring in Nigeria: Progress and challenges Open
Pollution is a major problem in developing countries.  There has been much studies on water pollution and its relation to communicable diseases with little attention to air pollution.  Air quality problem in sub-Saharan Africa is…
View article: Imprints of large-scale oscillations on river flow in selected Canadian river catchments
Imprints of large-scale oscillations on river flow in selected Canadian river catchments Open
Rivers within sub-tropical and temperate regions serve several purposes, including agricultural irrigation, hydro-power generation, and drivers of civilization. The impacts of six large-scale oscillation indices on river flow at three stat…