Fig. 1. Schematic diagram of the split-step beam propagation model

Fig. 2. Turbulence profiles at Sansha，Dachaidan and Hefei for four time periods of one day on January 1，2008

Fig. 3. Scintillation index of starlight as a function of zenith angle in Sansha，Dachaidan and Hefei under different observation altitudes

Fig. 4. Arrival angle of the far-field optical spot as a function of the zenith angle at four times of the day in Sansha，Dachaidan and Hefei under different observation altitudes

Fig. 5. Arrival angle fluctuation of the far-field optical spot as a function of the zenith angle at four times of the day in Sansha，Dachaidan and Hefei under different observation altitudes