Theoretical analysis on measurement error of forward scattering visibility meter
Forward scattering visibility meter (FSVM) is the main instrument to measure the visibility. The detection equation of FSVM was deduced based on the measuring principle and scattering theory. The error sources of FSVM and their uncertainty, which were caused by uncertainty of aerosol properties and performance change of optical electronic instrument, were analyzed by simulation calculation and statistical methods. The results show that the relative uncertainty of visibility caused by performance uncertainty is only 4% under the current technological conditions. The main error sources of FSVM are scattering phase function changes caused by aerosol properties and neglectable absorption effect. Because of uncertainty of aerosol properties,the relative uncertainty of FSVM reaches 28% actually. When the atmospheric aerosols are classified to fog,rural aerosol and urban aerosol,the relative uncertainties are 7%, 9% and 18% respectively under some specific conditions. The scattering phase function is sensitive to the change of scattering angle. The calibration of the scattering angle is necessary as the scattering angle changes in some cases such as transportion, erection and exploitation.The results can provide important theoretical support for the use, improvement and calibration of FSVM.
NETL
NSTL
万方数据
维普
