摘要
针对雨雾共存的特殊天气条件下现有大气衰减计算模型的不足,通过引入雨对雾的清除机制,对现有模型进行改进,提出一种更为精确、且能反映大气衰减动态特性的计算模型,并采用Monte-Carlo方法对激光在大气中的传输进行仿真分析。结果表明:降雨强度与雾的清除效应呈正相关,由于雨雾共存天气的雨量不大,随着雨对雾的清除,大气透射率逐渐增大;在降雨率为1 mm/h的情况下,平流雾的透射率大约在降雨5 h后趋于稳定,辐射雾则需要更长的时间。所提修正模型对无线光通信等相关领域中大气衰减的估计和评价具有参考意义。
Objective The coexistence of rain and fog is a common atmospheric phenomenon in winter. When laser is transmitted in rain and fog weather, the attenuation is not only affected by rain but also by fog. Because of the small rainfall rate, fog attenuation is usually greater than rain. Globally, numerous studies have been conducted on the transmission characteristics of laser in rain and fog individually, but research on laser transmission characteristics in rain and fog coexisting weather is inadequate. To the best of our knowledge, the interaction between raindrops and fog droplets has not been considered. In this study, based on the mechanism of rain clearing fog, we improve the existing models and propose a prediction model of atmospheric attenuation in rain and fog coexisting weather, which dynamically shows the changes of atmospheric attenuation and transmittance with time in rain and fog coexisting weather. We believe that the findings of this study will have reference significance for the estimation and evaluation of atmospheric attenuation in wireless optical communication and related fields.Methods In rain and fog coexisting weather,the precipitation process has a significant effect on fog removal.As fog is removed by raindrops,the scale distribution of fog will change.In this article,we employ the general dynamic equation considering wet deposition to study the dynamic change of fog with the removal of raindrops.Then,we use the lognormal scale distribution model of raindrops and Gamma distribution model of radiation fog and advection fog to calculate the total attenuation of rain and fog after clearing.Further,we employ Lambert-Beer law to reckon the transmittance of laser after a certain distance.Finally,the numerical results are compared with the Monte-Carlo simulation results to verify the rationality of the proposed model to a certain extent.Results and Discussions The rainfall intensity positively correlates with the fog removal effect.Since the rainfall in rain and fog coexisting weather is small,the
作者
俞任姣
李振华
来建成
王春勇
吴志祥
Yu Renjiao;Li Zhenhua;Lai Jiancheng;Wang Chunyong;Wu Zhixiang(School of Science,Nanjing University of Science&Technology,Nanjing,Jiangsu 210094,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2021年第13期147-154,共8页
Chinese Journal of Lasers
基金
国家自然科学基金(61971225)。
关键词
散射
大气衰减
雨雾共存天气
透射率
Monte-Carlo仿真
beam transmission
scattering
atmospheric attenuation
rain and fog coexisting weather
transmittance
Monte-Carlo simulation
