Measurements of the radiation fluctuations of a narrow divergent laser beam on 10 (ten) paths were made: 37, 130, 260 (2x130), 390 (3x130), 520 (4x130), 650 (5x130), 780 (6x130), 964, 1928 and 2048 m in the surface atmosphere in snowfalls. The wavelength is λ = 0.63 μm. The receiver was installed on the optical axis of the beam. The diameter of the receiver was 0.1 or 0.3, 0.8, 3.1 and 25 mm. It is established that the fluctuations the radiation of a laser beam increase with an scattering coefficient initially increase, and then do not increase (saturate) and decrease (on a 780 m path length for the diameter of the receiver 0.8 mm). In measurements with a receiver diameter of 0.1 or 0.3 mm, the saturation value is not determined as a function of the path length. With receiver diameters of 0.8 and 3.1 mm saturation value increases with the length of the path.
The distribution of the probability density of fluctuations of the intensity of the scattered radiation of a focused laser beam (0.63 μm) in the near – ground (surface) atmosphere in a haze on a 130 m long path was measured. It is established that the probability density distribution has one maximum. The distribution had the right asymmetry or had a form close to symmetric. The form of distribution does not depend on the wind speed and its perpendicular component to the path at close atmospheric conditions, at close values of the scattering coefficient and the size of the haze particles. Most experimental probability density distributions are approximated by the gamma distribution.
Measurements of the radiation fluctuations of a narrow diverging laser beam on 260 (2x130), 520 (4×130), and 780 (6x130) m in the surface atmosphere in snowfalls are carried out. The wavelength is λ = 0.63 μm. The receiver was installed on the optical axis of the beam. The diameter of the receiver was 0.8, 3.1 and 25 mm. It is established that the fluctuations in the radiation of a laser beam increase with the volume scattering coefficient first, and then do not increase (saturate) and decrease (on a 780 m long path). The level of fluctuations and the saturation value increase with the length of the path at a maximum snowflake size of 1 −3 mm with a receiver diameter of 0.8 and 3.1 mm.
Measurements of the distribution of probability density of fluctuations of the scattered radiation focused laser beam (0.63 μm) in the near-ground atmosphere in rain, drizzle and fog on the path length 130 m. It is established that the distribution of probability density unimodal and has a right skewness, standardized skewness and kurtosis increase with the growth of the scattering coefficient at close atmospheric conditions (with close values of the normalized variance and diameter (size) of the precipitation particles). The normalized skewness and kurtosis increase with the growth of the diameter (size) of particles of precipitation at close values of the coefficient of scattering. The shape of the distribution does not depend on the wind speed and its the perpendicular component to the path at close atmospheric conditions, at close values of the scattering coefficient. Most of the experimental distributions of probability density are approximated by a generalized gamma - distribution.
This report presents the results of measurements of fluctuations of the harmonic signal in Gaussian random noise. Shown the suitability of the criterion of the first output values approximating the distribution of the area of comparison for the approximation of experimental distributions measured for both dependent and independent samples of values of the harmonic signal in Gaussian random noise.
Measured temporal autocorrelation function the fluctuations of the scattered radiation of the focused laser beam (0.63 μm) in the surface atmosphere in rain, drizzle and fog on the highway with a length of 130 m. Found that the time correlation of the fluctuations of the scattered radiation of the focused laser beam in the rain and drizzle decreases with increasing perpendicular component to the path the wind speed is at close to atmospheric conditions (with close values of optical depth and particle size of atmospheric precipitation). The time correlation in the fog more, than the time correlation in the drizzle. It is an order of magnitude or more greater than in the rain.
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