关键词: 近地面层, 湍流大气, 到达角起伏, 大气稳定度, 各向同性, 各向异性

Abstract: In order to study the influence of turbulent atmosphere in the surface layer on the fluctuation of the
angle of arrival(AoA) of light propagation under different meteorological conditions, an optical
transmission experiment was carried out on a flat grass in the campus. A semiconductor laser
was used as the light source, and the light signal was received by a telescope with  focal length
of 1300 mm after transmitting 60 m to the receiving location, then a CCD camera was used to
shoot grayscale pictures of the light spot. Ratio of the AoA fluctuations in  vertical and
horizontal directions was calculated based on the position of the light spot on the photo.
The atmospheric turbulent refractive structure constant on the transmission path was also
calculated. Simultaneously, meteorological parameters near the transmission path, such as
temperature and wind speed, were measured so as to calculate the Richardson number as a
stability parameter. The results showed that when the Richardson number is greater
than 0.25, the ratio of vertical and horizontal AoA variances is greater
than 1.0; when the Richardson number is less than 0.25, the ratio of vertical and horizontal
AoA variances fluctuates around 1.0. Thus, it can be seen that atmospheric
turbulence is anisotropic under stable stratification conditions and isotropic under
unstable stratification conditions.

Key words: surface layer, turbulent atmosphere, AoA fluctuation, atmospheric stability, isotropy, anisotropy