Assessment of Tropospheric Radio Refractivity and Its Relationship with Meteorological Parameters Using a Low-Cost Weather Station Over Ikere-Ekiti, Nigeria

Abstract

This study investigates tropospheric radio refractivity and its dependence on meteorological parameters such as temperature, relative humidity, and atmospheric pressure—over Ikere-Ekiti, Nigeria, using in situ measurements from a locally fabricated low-cost automatic weather station. Hourly data were collected throughout September 2025 and used to compute surface radio refractivity (N) according to the Smith and Weintraub (1953) formula, as recommended in ITU-R P.453-15. Results reveal a strong diurnal pattern in which refractivity peaks during late evening and early morning hours (21:00–04:00 LT), coinciding with minimum temperature and maximum relative humidity. Refractivity drops sharply to its minimum in the early-to-mid afternoon (13:00–16:00 LT) when solar heating is at its peak. Statistical analysis shows that relative humidity is the dominant driver of refractivity variability, exhibiting a positive correlation of r = 0.78 with N. Atmospheric pressure shows a strong positive correlation (r = 0.85), while temperature exhibits a negative relationship (r = −0.70). The monthly mean refractivity was 378.76 ± 3.23 N-units, with values ranging from 373.17 to 384.35 N-units.These findings confirm that the tropical lower troposphere over southwestern Nigeria is characterized by significant short-term refractivity fluctuations largely driven by moisture variability. The study represents a wet-season baseline investigation, with September 2025 deliberately selected to characterize high-humidity tropospheric conditions prior to planned multi-season deployment. The results demonstrate the viability of low-cost sensor systems for atmospheric radio-propagation monitoring in resource-limited environments and provide site-specific baseline data for communication system design in the Ikere-Ekiti region