Physical Science International Journal

Seasonal Dynamics of Solar Radiation and Meteorological Parameters in a Tropical Nigerian Station

Opeyemi R. Omokungbe — 2025-10-17

Temporal variation of solar radiation with prevailing meteorological parameters focused on a specific location in the south-west Nigeria to provide detailed information required for climate studies and agricultural activities. Hourly and monthly solar radiation trends were analyzed using the variations in the temperature, relative humidity and wind speed from 2010 to 2013. This was with the purpose of determining the correction in the monthly trends of the solar radiation and meteorological parameters in Akure, south-west, Nigeria. Statistical analysis using Open Air project for R-statistics and the multiple linear regression (MLR) were carried out to establish correlation between solar radiation and prevailing meteorological parameters. Solar radiation has more significant impact on other meteorological parameter in the wet season at Akure while it drags other parameters with 1 – 2 months lag in the dry season. In the month August, which was characterized by the peak wet season, the station experiences rainfall break, extremely cloudy overcast and dominance of southwesterly wind. The cloudy atmosphere interrupts the incoming solar radiation with consequent effect of extremely humid and cold air temperature. This was why the low solar radiation aligned with high relative humidity and high wind speed in August while the temperature was the lowest. However, in dry season, the lag was as a result of onset of rainfall characterized by withdrawal of dry and cold northeasterly wind which interfered with response of boundary later to incoming radiation due to irregular heavy rainfall and rapid evaporation at this period. The results clearly aligned with predominant weather patterns in the tropical station influenced by back-and-forth movement of inter-tropical discontinuity during transition from dry to wet season.

Comparative Analysis of Rainfall Heights Over Geo-climatic Zones for Satellite Communication at Ku-Band in Nigeria

Samson Dauda Yusuf — 2025-10-18

Nigeria's diverse geo-climatic zones present varying challenges for satellite communications, particularly at Ku-band frequencies (12-18 GHz). Rainfall height is a critical parameter that directly influences signal propagation and the link margin, as such, must be taken into account when designing Ku-band satellite communication systems to ensure reliable and efficient communication. This study presents a comparative analysis of rainfall heights over Nigeria geo-climatic zones, the impact on Ku-band satellite communication system and a monthly zero degree isotherm height (km) across the selected locations. Data collected over three years from four locations, each representing a major geo-climatic zone of Nigeria, were analyzed using a purposeful sampling technique. The result shows seasonal variations of the Zero Degree Isotherm Height (ZDH) over Nigeria geo-climatic zones with lower heights occurring in January (4.1 to 4.15km) and December (4.18 to 4.2km) while peak heights occur during the middle months of the year (July-August), reaching approximately 4.42-4.43km. ESUT (Enugu) and FUTA (Akure) shows slightly higher values than PJAA (Abuja) and FUGUS (Gusau) most times of the year, particularly in August where it reaches about 4.43km. The distribution of measured ZDIH across the zones varies (4.109km – 4.431km) as against 4.5km predicted by the International Telecommunication Union-Radio (ITU-R). The measured rain height ranges from 4.46km to 4.79km across the zones as against 4.86km predicted by ITU-R for the same zones. ITU-R model maintains a constant height throughout the period, showing no seasonal variation. The study reveals that the ITU-R model overestimates the ZDIH by approximately 4.4-5.6% and the rain height by about 4.1-5.2% across Nigerian zones. Therefore, this substantial difference must be put into consideration as an important parameter in Meteorology and for estimating rain attenuation in satellite communication systems in Nigeria to avoid the overestimation of rain attenuation and subsequent over-engineering of satellite link budgets.

Passive Optimization of Indoor Thermal Comfort Using Bio-based Materials: An Experimental Study in a Classroom in Burkina Faso

Ousmane Ouedraogo — 2025-10-29

In the Sahel region, which is characterized by extreme temperatures and energy insecurity, improving thermal comfort in school buildings is a major challenge. This study evaluates the effectiveness of a bio-based construction solution integrated into the envelope of a typical school building in Burkina Faso. This solution is a bio-based eco-material made from plant aggregates (rice husks) and plant fibers (kapok) used as a false ceiling and wall coating. A dual approach was adopted: experimental measurements in situ during the hot season and dynamic thermal modeling using Python. The results show a reduction in maximum indoor temperature of up to 8°C, a thermal phase shift of approximately 5 hours, and a decrease of more than 57% in the intensity of thermal discomfort (>32°C) when the eco-material is used in combination with a false ceiling and wall coating. In addition, the theoretical cooling energy demand is reduced by 30%, highlighting the energy benefits of these materials in terms of energy efficiency. These performances, combined with the accessibility of local resources and ease of implementation, position these solutions as credible alternatives for the design of bioclimatic schools adapted to the Sahelian climate. The study also highlights limitations related to hygrothermal sustainability and calls for further work to assess the impact perceived by users and reproducibility on a large scale.

Numerical Analysis of the Combined Effect of BSF Thickness and Doping on the Performance of an a-Si:H/c-Si SHJ Cells Cell

Jacques Joachim FAYE — 2025-10-31

We numerically study how the rear n⁺-a-Si:H Back-Surface-Field (BSF) thickness and doping co-determine the performance of a-Si:H(n⁺)/c-Si(n)/a-Si:H(p⁺) silicon heterojunction (SHJ) solar cells. Using a two-diode formalism coupled to TCAD SILVACO-ATLAS drift–diffusion under AM1.5G and , we sweep a thin BSF window ( ) and its doping ( ) while keeping the optical stack and interface-defect sets fixed to isolate the electrical role of the rear contact. A thin, highly doped BSF reduces rear-surface recombination and strengthens carrier selectivity, yielding a small but systematic Voc increase ( in our setup), a modest improvement consistent with lower effective series/recombination losses ( ), and a broadly stable . The resulting efficiency peaks when combining a thin BSF with high doping; by contrast, too-thin layers under-passivate and too-thick layers introduce resistive and potential optical penalties. Modeling includes SRH and Auger recombination with fixed trap sets, standard mobility/bandgap temperature dependences, and constant front/back optical conditions, thereby attributing observed performance changes specifically to BSF thickness/doping. For clarity and design use, we report baseline vs. near-optimum KPIs ( ), indicating an absolute η gain of percentage points under AM1.5G, 25 °C. A brief sensitivity note (series resistance; rear interface traps) explains how further increases in resistive or defect-related losses would primarily round the knee (lowering ) and slightly reduce Voc, consistent with our trends. Overall, these results provide practical guidance for rear-contact engineering in SHJ cells and align with recent literature on passivating selective contacts, while deliberately keeping other surface-property variations outside the present scope.