Abstract:
Using the softwares such as Fortran,Matlab and Origin to deal with the turbulence and visibility data and draw figures the comparison of turbulent characteristics anong a haze process on 4 December 2013, a fog process from 7 to 9 December 2013 and a sunny day on 3 December 2013. The results show that the average speed of wind, the average kinetic energy, turbulence kinetic energy, turbulence intensity, friction velocity, momentum transfer, and heat transfer on both the haze day and sunny day illustrate an evident diurnal variation, while there was no obvious diurnal variation on the fog day. There were also differences among the value of the turbulence parameters on haze day, fog day and sunny day. The normalized variance of the three-dimensional (3D) winds (u, v and w) in the near-neutral stratification was almost constant on the haze day, fog day and sunny day; the normalized variance of 3D winds on the haze day is 3.15, 2.72 and 1.17 respectively; on the fog day it is 3.11, 2.45 and 1.25, respectively; on the sunny day it is 3.40, 3.45 and 1.50, respectively. The haze day and fog day's normalized variance of 3D winds, normalized turbulence kinetic energy and the ratio of horizontal moisture momentum vs. vertical moisture momentum meet the 1/3 law with the stability parameter in the unstable condition. The haze day, fog day and sunny day's normalized turbulence kinetic energy meet the 1/3 law with the stability parameter in both stable and unstable conditions. The haze day, fog day and sunny day's normalized variance of temperature and moisture meet the -1/3 law with the stability parameter in the unstable condition, and the haze day, fog day and sunny day's normalized variance of temperature meet the -2/3 law with the stability parameter in the stable condition. The fog day's normalized spectra of 3D winds fit better with the Kansas spectra than the haze day's and sunny day's. The haze day's peak frequency of 3D winds is about 0.01 Hz, the fog day's peak frequency of the u spectra is about 0.004 Hz, the fog day's peak frequency of the v/w spectra is about 0.1 Hz, and the sunny day's peak frequency of 3D winds is about 0.01 Hz. The conclusions are as follows: the boundary layer structure on the fog day is different from that on either the haze day or sunny day.The normalized variance of the wind, turbulence kinetic energy, temperature and humidity on the fog day, haze day and sunny day all meet the Monin-Obukhov similarity theory in the unstable condition. The fog day's normalized spectra of 3D winds accords better with the Monin-Obukhov isotropic theory than the haze day's and sunny day's. The haze day and sunny day include mainly the mechanical turbulence, while the fog day includes both the mechanical turbulence and thermal turbulence.