Numerical modeling of the efficiency of optical communication channels taking into account the combined effects of hydrometeors and atmospheric turbulence

Aerosols and hydrometeors are primary modulators of near-infrared radiative transfer, governing extinction and visibility degradation in FSO links. We analyze size-dependent scattering regimes via the size parameter x=2πr/λ. Rayleigh scattering (r≪λ) is negligible in the NIR under high aerosol loading; Mie scattering (r≈λ) dominates for accumulation-mode aerosols, while geometric scattering (r≫λ) applies to coarse particles and fog droplets.

We estimate path attenuation from meteorological visibility using the empirical Kim model as a fitting surrogate. For V<0.5 km, q=0 yields wavelength-independent attenuation, consistent with geometric optics for large droplets, though no direct Mie integration over the size distribution is performed. Power laws handle rain and snow. Turbulence-induced intensity scintillation is modeled separately: lognormal for weak turbulence (σ²_R<0.3) and Gamma–Gamma for moderate-to-strong. Aerosol attenuation is determined as fixed path loss, reducing average received power, while turbulence provides multiplicative stochastic modulation of instantaneous intensity. Average BER integrates instantaneous BER over the turbulence-induced probability density function, BER_avg = ∫ BER(I·S) p(I) dI, where S = P_avg/P_sens is the ratio of average power to receiver sensitivity.

The system assumes OOK at λ=1550 nm, P_tx=5 dBm, P_sens=-30 dBm (at BER=1e-9), L=1.0 km, and L_sys=3 dB. For severe aerosol loading (V=0.15 km, C_n²=1e-14), the Kim model yields an attenuation of 26.08 dB/km; total loss is 29.08 dB. The combined model predicts BER=1.038e-9, confirming that empirical attenuation and statistical turbulence parameterizations, integrated into a single pipeline, quantitatively assess link operability under dense fog and strong turbulence.

Our contribution integrates classical attenuation and turbulence sub-models into a unified, open-source computational pipeline with automatic regime selection, enabling rapid end-to-end link performance assessment for urban FSO deployments. When combined with multi-wavelength extinction data and appropriate regularization, the forward model could also serve in aerosol characterization; however, retrieval of microphysical properties is beyond the scope.