为了研究降雨对近红外辐射的衰减,定量评估降雨对近红外设备的影响,在雨滴谱分布二元函数模型建立的基础上,提出了一种雨滴谱分布数据库的建立方法,对LAWS和PARSONS在美国华盛顿地区测量的雨滴谱分布数据进行拟合,建立雨滴谱分布数据库。基于雨滴谱分布数据库,结合米散射理论和衰减系数公式,得到了1μm,2μm和3μm波长近红外辐射的消光效率因子与雨滴直径的关系曲线,并计算了在降雨量分别为0.25mm/h,1.25mm/h,2.5mm/h,12.5mm/h,25mm/h和50mm/h条件下的近红外辐射衰减系数。结果表明,不同降雨量条件下,对于雨滴谱分布的函数关系式,正态分布具有更好的拟合效果; 消光效率曲线的包络线随波长的增大而增大;拟合衰减系数和降雨强度的函数关系发现,指数函数具有很好的拟合效果。该计算结果对研究降雨对近红外辐射的衰减具有重要意义。

In order to study the attenuation of near infrared radiation by rainfall and quantitatively estimate the effects of rainfall on near infrared devices, on the basis of the establishment of two-element function model of raindrop distribution, a method for establishing the database of raindrop distribution was proposed. After the fitting of raindrop distribution data measured by LAWS and PARSONS in Washington region of the United States, raindrop distribution database was established. And then, combining with Mie scattering theory and attenuation coefficient formula, the relationship curves between extinction efficiency factor and raindrop diameter under 1μm,2μm and 3μm wavelength near infrared radiation were obtained. Under the condition that rainfall was respectively 0.25mm/h,1.25mm/h,2.5mm/h,12.5mm/h,25mm/h and 50mm/h, the attenuation coefficients of near infrared radiation were calculated. The results show that, under different rainfall conditions, normal distribution has better fitting effect on function relation of raindrop spectral distribution. The envelope of extinction efficiency curve increases with the increasing of wavelength. After the fitting of function relation between attenuation coefficient and rainfall intensity, it is found that, the exponential function has the good fitting effect. The calculated results are important for studying the attenuation of near infrared radiation by rainfall.