Diurnal Atmospheric Turbulence Effects on 1.57 μm Ground-to-air Illumination Laser System Performance

This study investigated the performance degradation of a 1.57 μm ground-to-air illumination lasersystem under varying atmospheric turbulence conditions. A time- and altitude-resolved simulation framework based on the Hufnagel–Valley model was developed using site-specific measurements of the refractive index structure parameter (C 2n ) collected over one week in March 2025, along with windspeed data from the regional meteorological agency. Received energy was estimated over a full diurnal cycle using a four-step propagation model comprising forward transmission, target interaction, backscattering, and receiver filtering. Simulation results showed substantial temporal variation in system performance, driven by turbulence fluctuations. The highest return energy occurred at 21:00 (4.38 mW), while the lowest was at 12:00 (1.01 mW), corresponding to a 77% decrease in signal strength and a 129% increase in fluctuation. Although the timing may vary, the results consistently showed maximum returns 2–3 hours after sunset, when turbulence is weakest, and minimum returns around midday, when turbulence peaks. These findings underscore the significant impact of diurnal turbulence on the stability and efficiency of laser-based systems and support the importance of optimized operational scheduling. Future work will focus on experimental validation under comparable atmospheric conditions.