eng Science and Education Publishing International Journal of Physics 2333-4576 2026-08-14 14 2 36 47 10.12691/ijp-14-2-3 IJP20261423 article Wongnigu¨¦ Allassane Soro soro.wongnigue@upgc.edu.ci 1 Amadou Soumahoro 1 Douatia Kon¨¦ 1 2 Aladji Kamagat¨¦ 2 Mathematics Physics Chemistry, LaTIATE Laboratory, Universit¨¦ Peleforo Gon Coulibaly, Korhogo, C?te d¡¯Ivoire Unmanned aerial vehicle (UAV)-assisted free-space optical (FSO) communication is a promising solution for rapidly deployable, high-capacity wireless networks. However, realistic channel characterization in tropical environments remains challenging because atmospheric attenuation, turbulence, pointing errors, and angle-of-arrival (AoA) fluctuations are often investigated independently and rarely using long-term site-specific meteorological data. This paper presents a unified statistical framework for modeling a UAV-assisted FSO link under the tropical savanna climate of Korhogo, northern Côte d¡¯Ivoire. The proposed model jointly incorporates weather-dependent attenuation caused by rain, fog, humidity, and dust, Málaga-distributed atmospheric turbulence, pointing errors, and AoA fluctuations within a heterodyne-detection decode-and-forward relay architecture. Atmospheric attenuation parameters are derived from six years (2020¨C2025) of meteorological observations collected by the Korhogo station of the National Meteorological Agency (ANAM), enabling realistic channel characterization. Closed-form channel statistics are employed to evaluate the signal-to-noise ratio (SNR) and bit-error rate (BER). The results show seasonal atmospheric attenuation ranging from 0.81 dB/km during the dry season to 3.10 dB/km under severe rainy conditions. Increasing the UAV altitude from 200 m to 500 m extends the communication range from 2.5 km to 4.5 km for an SNR threshold of 10 dB, while the reliable transmission distance at a BER of 10?³ increases from 2.5 km to 3.2 km. More importantly, the analysis reveals a distance-dependent altitude trade-off. Beyond approximately 5 km, humidity-induced attenuation and beam divergence outweigh turbulence mitigation, challenging the common assumption that higher UAV altitudes always improve FSO performance. These findings provide practical design guidelines for deploying reliable UAV-assisted FSO systems in tropical environments. https://pubs.sciepub.com/ijp/14/2/3/ijp-14-2-3.pdf Angle-of-Arrival fluctuations Atmospheric attenuation Atmospheric turbulence Channel characterization M¨¢laga distribution Pointing errors UAV-FSO communications