Traditional microwave communication has a limited bandwidth. Although satellite-ground laser communication has significant advantages, atmospheric turbulence causes the laser to experience spatial phase distortion, severely restricting communication performance. Currently, the multi-layer atmospheric turbulence phase screen method is an important approach for studying the atmospheric turbulence effect in satellite-ground links. However, the existing numerical simulation methods of multi-layer atmospheric turbulence phase screens for satellite-ground links have deficiencies. They are unable to accurately depict the variation characteristics and the dynamic evolution process of satellite-ground atmospheric turbulence at different altitudes. This research aims to construct an accurate dynamic atmospheric turbulence model for satellite-ground links, effectively evaluate its impact on the characteristics of laser transmission, and promote the practical application of satellite-ground laser communication technology.

Given that the impact of atmospheric turbulence on the laser is concentrated in the altitude range of 0?20 km, this area is divided into the boundary layer, troposphere, and stratosphere. According to the non-Kolmogorov turbulence power spectrum, the H-V 5/7 model, and the model of the spectral index varying with altitude, the atmospheric refractive index structure constants and the turbulence spectral indexes at different altitudes are calculated. The power spectrum inversion method with low-frequency harmonic compensation is applied to generate a three-layer atmospheric turbulence phase screen with a non-Kolmogorov spectrum, simulating the turbulence effects in different atmospheric layers. Meanwhile, based on the principle of Fresnel diffraction and considering the factors such as the coherent length of atmospheric turbulence, a three-layer atmospheric turbulence beam transmission model for satellite-ground links is constructed. Considering the dynamic characteristics of atmospheric turbulence in reality, the rotation truncation phase screen method is adopted. By controlling the variables such as the distance between the center of the sub-phase screen and the center of the large phase screen, the size of the sub-phase screen, and the included angle between adjacent sub-phase screens, and combining with the average wind speeds in different atmospheric layers, the initial phase screen is rotated and truncated to obtain a sequence of dynamic atmospheric turbulence phase screens, constructing a three-layer dynamic atmospheric turbulence phase screen model for satellite-ground links.

The simulation results show that the order of sub-harmonic compensation affects the simulation accuracy of the atmospheric turbulence phase screen. The phase structure function with the 10th-order sub-harmonic compensation is close to the theoretical value and can effectively represent the spatial phase disturbance caused by atmospheric turbulence (Fig. 6). A radius-variable rotation truncation method is proposed, which improves the periodic change phenomenon of the light intensity scintillation index and can accurately simulate the variation characteristics of the light field in a relatively long time sequence (Fig. 8 and Fig. 9). In addition, the light intensity scintillation index of the Gaussian beam after being modulated by the three-layer dynamic atmospheric turbulence phase screen for satellite-ground links has a high degree of agreement with the theoretical value, and the model can accurately represent the average atmospheric wind speed, enabling accurate simulation of laser transmission between the satellite and the ground (Fig. 11 and Fig. 12).

In present study, a three-layer dynamic atmospheric turbulence model for satellite-ground links based on the non-Kolmogorov power spectrum is constructed. Verified by various methods, this model has a high accuracy in simulating the atmospheric turbulence effect for satellite-ground links. Specifically, after the compensation of the 10th-order low-frequency harmonic, the variation trend of the phase structure function is highly consistent with the theoretical result. After being modulated, the Gaussian beam shows obvious light intensity scintillation, and the light intensity scintillation indices under different zenith angles are consistent with the theoretical values. The radius-variable rotation truncation method can accurately simulate the changes in wind speeds in different atmospheric layers, enabling accurate simulation of laser transmission between the satellite and the ground. In conclusion, this model can effectively depict the dynamic evolution process of satellite-ground atmospheric turbulence and accurately evaluate its impact on the characteristics of laser transmission, providing an important theoretical and technical support for the development of satellite-ground laser communication technology.