Spatiotemporal Dynamics of Near-Surface Micro-Scale Refractivity Gradient: Implications for Terrestrial Wireless Communications

Abstract

This study investigates the spatiotemporal dynamics of near-surface micro-scale radio refractivity and its implications for terrestrial wireless communications across Nigeria, with particular interest in the near-surface atmosphere where modern street-level communication infrastructure increasingly operates. Using spatially continuous MERRA-2 data at 2 and 10 m altitudes, near-surface refractivity and the micro-scale refractivity gradient were estimated and spatially represented through ordinary kriging to map contours across Nigeria. The results reveal a pronounced geographical structure in near-surface refractivity, increasing from the relatively dry northern interior toward the more humid southern and coastal regions, with values of approximately 310–320 N-units in parts of the north and up to about 390 N-units in the south at both altitudes. The estimated micro-scale refractivity gradient is predominantly negative and becomes progressively stronger toward central and southern Nigeria, with the most pronounced values reported around the southeastern and coastal environments. These show that the near-surface atmosphere is not spatially uniform and that relatively small vertical changes within the lowest few meters produce substantially different propagation conditions. These variations are particularly important for microwave links and other terrestrial systems operating close to the ground, because strong refractivity gradients promote atmospheric trapping, with consequences including extended radio range, unexpected distant-signal reception, co-channel interference, multipath propagation, fading, unstable links and radar anomalies. Overall, the study provides a useful spatially explicit foundation for incorporating micro-scale atmospheric variability into wireless network planning, path-clearance assessment, interference management and the development of more resilient terrestrial communication infrastructure in Nigeria.

Keywords: near-surface refractivity, micro-scale refractivity gradient, localized wireless propagation impairments, terrestrial wireless communications, chaotic micro-environment

DOI: 10.7176/JNSR/17-2-05

Publication date: September 28th 2026