Research On The Simultaneous Measurement Method Of Atmospheric Visibility And Turbulence Intensity

Atmospheric visibility and turbulence are important meteorological factors in air quality prediction,climate environment model,light propagation and optical communication.For atmospheric transparency,the intuitive reflection is atmospheric visibility,which is both a meteorological element in the field of transportation and safety,and an important feature of air pollution in the field of environmental monitoring;Similarly,the refractive index fluctuation caused by atmospheric turbulence will destroy the coherence of light,optical image caused by the fuzzy,which is a difficult problem in astronomical observations.They are often measured separately by the conventional instruments,but the interaction between aerosol(closely relate to visibility)and turbulence may make influence on their measurement accuracy.In order to solve this problem and overcome the shortcomings of existing discrete measurement scientific instruments,a novel instrument,the atmospheric visibility and turbulence optical meter(AVTOM),is developed to synchronously measure atmospheric visibility and turbulence intensity through a transmission method.The specific work is as follows:(1)We combine atmospheric radiative transfer theory with the theory of fluctuating light in random medium,and overcome the problem of simultaneous measurement of atmospheric visibility and turbulence intensity,and realize the simultaneous measurement of atmospheric visibility which reflects the transparency of the atmosphere and atmospheric refractive index structure constant which reflects atmospheric turbulence intensity.(2)The overall design scheme of synchronous measuring optical system prototype is proposed.The optical transmitting unit,the optical receiving unit,the instrument control unit and the data receiving unit of the system are designed respectively.The ZEMAX software is used to design and simulate the collimation lens of the system.The structure of the system is designed by using the SOLIDWORKS software.(3)We analyzed the software requirements of the system,completed the design and compilation of data acquisition software,and proposed a crest data filtering algorithm for system data acquisition.(4)A semi-automatic calibration method is proposed to analyze the measurement error.We validated the measurement results by comparing to other two conventional instruments(OWI OSI-430 and CAST3A)in July 2017,at Nanjing University Xianlin Campus.They agree well with the relative differences of 4.7%for the visibility and 3.5%for the turbulence intensity,respectively.We further demonstrated their dramatic variabilities under the different weather or aerosol loadings through the synchronous measurements,which may be associated with the aerosol-turbulence-interaction.In this paper,the ground-based synchronous optical system,which is designed and developed successfully,is of great significance for atmospheric environmental monitoring,air quality prediction,radiation climate and environmental effects.