Journal Articles

Vertical Distribution of Cloud Area Fraction and Associated Cloud Radiative Effects over East Africa Using MERRA-2 Reanalysis and CERES (2000–2025) Data

2026-07-21T12:35:06Z

Vertical Distribution of Cloud Area Fraction and Associated Cloud Radiative Effects over East Africa Using MERRA-2 Reanalysis and CERES (2000–2025) Data Geoffrey W. Khamala; John W. Makokha; Churchill Wanyera; Kanike Raghavendra Kumar; Mansour Almazroui; Pelati Althaf; Aqil Tariq The Cloud Area Fraction (CAF) and Cloud Radiative Effect (CRE) are among the key metrics for understanding Earth’s climate, as they modulate shortwave and longwave radiation. This study, therefore, analyzes the vertical distribution of CAF and their associated CRE over East Africa (EA) using the Modern-Era Retrospective Analysis for Research and Applications Version (MERRA-2) reanalysis and Clouds and the Earth’s Radiant Energy System (CERES) observational data from 2000 to 2025. The vertical CAFs for low, middle, and high clouds are computed at pressure levels and spatially averaged over EA. These are used to derive shortwave CRE (CREin Wm− 2), longwave CRE (CREin Wm− 2), and net CRE (in Wm− 2) from all-sky and clear-sky radiative fluxes. The validation of MERRA-2 CAF against CERES observations showed it to be reliable (r = 0.749), supporting its use for analyzing cloud-radiation patterns, including verti cal cloud distribution. The study of vertical CAF and CRE over EA using MERRA-2 reveals a strongly stratified cloud climatology shaped by topography, lake impacts, and large-scale circulation. The vertical CAFs at Low, mid, and high clouds show distinct spatial and temporal patterns, with high clouds intensifying the most with more than 60% of the total CAF (0.256), while the contribution of the low CAF against the total covers 18% (0. 076) is the least. Further, the spatiotemporal CRE is dominated by shortwave cooling, ranging from − 14.71 to -54.36 W m−2, which moderates regional temperatures. Cloud layers interact to influence rainfall: low clouds enhance local convection, mid clouds regulate moisture transport, and high clouds mark mature convective systems. This collectively reinforces EA’s bimodal rainfall pattern and highlights the critical role of clouds in regional climate dynamics. This study recommends future analyses that integrate long-term model outputs with satellite and ground-based observations to validate cloud patterns. Such emphasis should focus on the CREs of low, middle, and high clouds, their links to rainfall, and model uncertainties to improve understanding of the role of cloud dynamics over EA’s climate

THE IMPACT OF STAKEHOLDER PARTICIPATION ON THE EXECUTION OF STREET LIGHTING PROJECT IN TURKANA COUNTY, KENYA

2026-07-21T12:08:25Z

THE IMPACT OF STAKEHOLDER PARTICIPATION ON THE EXECUTION OF STREET LIGHTING PROJECT IN TURKANA COUNTY, KENYA James Eukot Lotom; Harriet Jepchumba Kidombo; Anthony Wainaina Ndungu Project implementation is a critical phase of the project lifecycle that directly determines project success. Sustainable organizational performance relies on structured project management procedures rather than arbitrary methods, which frequently lead to unpredictable outcomes. This study assessed the influence of stakeholder engagement on the implementation of street lighting projects in Turkana County, Kenya. Anchored on Stakeholder Theory, the study adopted a cross-sectional survey design. The target population consisted of 34 Chief Officers/M&E Experts, 6 Sub-county Quantity Surveyors, 6 Sub county Electrical Engineers, 6 M&E Focal Persons, 6 Project Implementation Committee Chairpersons, 6 Sub-county Financial Directors, and 6 Sub-county Procurement Officers. Simple random sampling was used to select 27 Chief Officers/M&E Experts, while a census approach was adopted for all other categories. Data were collected using questionnaires and document analysis checklists. Quantitative data were analyzed using frequencies, means, and standard deviations, while hypotheses were tested via simple linear regression using SPSS Version 25 and the Hayes PROCESS Macro v4.1. The findings demonstrated a significant relationship between stakeholder management and the implementation of street lighting projects (p < 0.05). Actively involving stakeholders in decision-making processes improved the quality of project monitoring and evaluation (M&E) reports, ultimately enhancing project execution. Furthermore, the interaction term (X \times W) explained an additional 14.5% of the variance in project implementation (Delta R^2 = 0.145), and the overall model was statistically significant (p < 0.05). This indicates that the independent and moderator variables jointly predict the dependent variable. Notably, the results confirm that the moderator variable (stakeholder engagement) significantly alters the relationship between M&E capacity and the implementation of street lighting projects.

Long-term characterisation and discrimination of aerosol types across Africa using AERONET observations (1998–2024

2026-07-21T09:25:40Z

Long-term characterisation and discrimination of aerosol types across Africa using AERONET observations (1998–2024 Yonah Situma; John W. Makokha; Geoffrey W. Khamala; Kanike Raghavendra Kumar; Richard Boiyo; Geoffrey W. Khamala, Geoffrey W. Khamala Accurate identification and classification of atmospheric aerosols remain a significant challenge across Africa, limiting the precise assessment of their climatic effects. This study presents a comprehensive analysis of aerosol characteristics and aerosol types using ground-based observations from twelve selected AErosol RObotic NETwork (AERONET) sites across Africa during 1998–2024. Key aerosol optical properties, including aerosol optical depth (AOD), Ångstr¨ om exponent (AE), fine-mode fraction (FMF), and single scattering albedo (SSA), were examined to characterize their temporal variability and identify dominant aerosol types. A multivariate scattering-based classification approach was employed to improve aerosol discrimination. The results indicate that dust, biomass-burning, and urban/industrial aerosols are the predominant aerosol categories across the continent. Fine- and coarse-mode absorbing aerosols were particularly prevalent in rural tropical regions, highlighting the coexistence of natural and anthropogenic emission sources. Moreover, extensive biomass- burning activity in tropical Africa contributes substantially to regional aerosol loading and complexity. These findings provide valuable insights for improving the representation of aerosol processes in climate models and enhancing assessments of aerosol–climate interactions over Africa. The proposed multivariate framework advances aerosol classification and source attribution, supporting a better understanding of aerosol-related environmental and climatic impacts across the continent.

Long-term characterisation and discrimination of aerosol types across Africa using AERONET observations (1998–2024

2026-07-21T09:19:13Z

Long-term characterisation and discrimination of aerosol types across Africa using AERONET observations (1998–2024 Yonah Situma; John W. Makokha; Peter N. Khakina; Geoffrey W. Khamala; Kanike Raghavendra Kumar; Richard Boiyo Accurate identification and classification of atmospheric aerosols remain a significant challenge across Africa, limiting the precise assessment of their climatic effects. This study presents a comprehensive analysis of aerosol characteristics and aerosol types using ground-based observations from twelve selected AErosol RObotic NETwork (AERONET) sites across Africa during 1998–2024. Key aerosol optical properties, including aerosoloptical depth (AOD), Ångstr¨ om exponent (AE), fine-mode fraction (FMF), and single scattering albedo (SSA), were examined to characterize their temporal variability and identify dominant aerosol types. A multivariate scattering-based classification approach was employed to improve aerosol discrimination. The results indicate that dust, biomass-burning, and urban/industrial aerosols are the predominant aerosol categories across the continent. Fine- and coarse-mode absorbing aerosols were particularly prevalent in rural tropical regions, highlighting the coexistence of natural and anthropogenic emission sources. Moreover, extensive biomass- burning activity in tropical Africa contributes substantially to regional aerosol loading and complexity. These findings provide valuable insights for improving the representation of aerosol processes in climate models and enhancing assessments of aerosol–climate interactions over Africa. The proposed multivariate framework advances aerosol classification and source attribution, supporting a better understanding of aerosol-related environmental and climatic impacts across the continent.