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在观测激光信号在雨中传输时,其衰减比率随着雨滴的大小而变化,雨滴越小衰减越大。根据Mie理论和Joss等人雨滴谱分布,分析了粒子尺度及不同波长对激光散射的影响,并且计算了衰减效率因子与粒子尺度的关系,推导了光波在单球粒子和稀疏分布雨中衰减的计算公式,得到了衰减与降雨率之间的确定关系。通过数值计算发现:小雨粒子各个方向的散射光强明显大于大雨粒子的散射光强;前向散射光强随粒子半径的增加,整体呈现增加趋势,并出现了明显的上下震荡;激光信号通过雨介质传输时,小雨衰减系数较大,雷暴雨衰减较小。这解释了在实验中观测到的现象,激光信号在小雨中的衰减要比大雨中的衰减大。
When the observed laser signal is transmitted in the rain, the attenuation ratio changes with the size of the raindrop, and the smaller the raindrop is, the larger the attenuation is. According to Mie theory and Joss et al. Raindrop spectral distribution, the effects of particle size and different wavelengths on laser scattering are analyzed. The relationship between the attenuation efficiency factor and the particle size is calculated and the attenuation of light waves in single-particle and sparsely distributed rain is deduced The formula determines the relationship between attenuation and rainfall rate. The numerical results show that the scattered light intensities in all directions of rain particles are obviously larger than those of heavy rainfall particles. The intensity of forward scattering increases with the increase of particle radius, and the upward and downward oscillations appear. Medium transmission, rain attenuation coefficient larger thunderstorm attenuation smaller. This explains the phenomena observed in the experiments where the laser signal attenuates more in light rain than in heavy rain.