A new method for estimating aerosol mass flux in the urban surface layer using LAS technology

Abstract

Abstract. Atmospheric aerosol greatly influences human health and the natural environment, as well as the weather and climate system. Therefore, atmospheric aerosol has attracted significant attention from society. Despite consistent research efforts, there are still uncertainties in understanding its effects due to poor knowledge about aerosol vertical transport caused by the limited measurement capabilities of aerosol mass vertical transport flux. In this paper, a new method for measuring atmospheric aerosol vertical transport flux is developed based on the similarity theory of surface layer, the theory of light propagation in a turbulent atmosphere, and the observations and studies of the atmospheric equivalent refractive index (AERI). The results show that aerosol mass flux can be linked to the real and imaginary parts of the atmospheric equivalent refractive index structure parameter (AERISP) and the ratio of aerosol mass concentration to the imaginary part of the AERI. The real and imaginary parts of the AERISP can be measured based on the lightpropagation theory. The ratio of the aerosol mass concentration to the imaginary part of the AERI can be measured based on the measurements of aerosol mass concentration and visibility. The observational results show that aerosol vertical transport flux varies diurnally and is related to the aerosol spatial distribution. The maximum aerosol flux during the experimental period in Hefei City was 0.017 mg m −2 s −1 , and the mean value was 0.004 mg m −2 s −1 . The new method offers an effective way to study aerosol vertical transport in complex environments.

Scintillometry in urban and complex environments: a review

“…However, the imaginary part potentially contains useful information about turbulence (such as the outer length scale) and absorption and scattering by aerosols or trace gases. Yuan et al (2015) used a LAS (λ = 0.62 μm) to investigate fluctuations in aerosol concentration at a university campus surrounded by busy roads in the city of Hefei, China, and subsequently extended the method to estimate aerosol mass flux using similarity theory (Yuan et al, 2016), although no direct evaluation was presented. Although several practical and theoretical uncertainties still require quantification, more routine analysis of the imaginary part of Cn 2 has potential.…”

Quantitative verification of the turbulence barrier effect during heavy haze pollution events

“…There are some past studies which used the eddy covariance technique to determine the number concentration flux of fine particles in Stockholm (Vogt et al 2011), London (Harrison et al 2012), Helsinki (Ripamonti et al 2013) and so on. However, obtaining the fine particles mass flux is more important for many applications (Yuan et al 2016). The number concentration flux of fine particles is always dominated by high concentrations of smaller particles, which cannot represent the mass flux directly.…”

Aerosol vertical mass flux measurements during heavy aerosol pollution episodes at a rural site and an urban site in the Beijing area of the North China Plain

“…The use of eddy covariance principles to measure sensible heat fluxes has been widely performed (Lee, 2004). Current sensible heat fluxes can also be obtained using a large aperture scintillometer (LAS) based on the light propagation theory and atmospheric surface layer similarity theory (Zeweldi et al, 2010). This configuration makes it possible to achieve aerosol mass flux measurements using the same principles.…”