Experimental studies on fluctuation properties of dust, turbulence and electric field during floating dust weather in Lanzhou

Abstract

In this paper, real-time measurements of three-dimensional wind speed, electric field and dust concentration during the floating-dust event were carried out in Lanzhou. The scaling relationship of different physical quantities in spectral space and the effect of turbulent events on dust and heat transport are studied by spectral method and octant analysis method. Our results show that the logarithmic value of power spectrum of dust concentration, relative humidity (RH), streamwise and vertical wind speed (u and w) between 0.06 Hz and 0.435 Hz meets the linear relationship with the logarithmic value of frequency (f), and decreases with the logarithmic value of f. For different stages, in the frequency range from 0.06 Hz to 0.218 Hz, the slope of the u first increases and then decreases. The slope of dust concentration and RH did not change significantly in the development stage, but decreased in the decay stage. The slope of the temperature (T) first decreases and then increases. In the frequency range from 0.218 Hz to 0.435 Hz, the slope of u and RH first increase and then decrease. The slope of the dust concentration does not change significantly during the development stage and decreases in the decay stage. The slope of w first increases and then decreases. In the second stage, the contribution of ejection and sweep events to the turbulent motion increases. For dust and heat transport, the O₅ and O₈ have a larger number contribution. Although the number and intensity contribution ratio of all octants increased or decreased in the second and third stages, in terms of the intensity of a single event, the contribution of all octants to the dust and heat transport increased.