Dust Haze over the North China Plain

Based on monitoring from AERONET stations in the Beijing region in the twenty first century, it is found that, during transport of dust haze with the aerosol optical depth up to 4.0–4.5, the optical and microphysical characteristic of dust aerosol are determined by coarse particles with modal radii of ∼2–4 μm and a mass content of dust aerosol reaching 11–12 g/m 2 . Data of monitoring from the Beijing and Xinglong stations in April 2006 and from the Beijing-CAMS station in March 2021 indicate that the imaginary part of the refractive index of dust aerosol under the conditions of optically dense dust haze is comparatively small, from 0.0005 to 0.003, with 54 and 77% detection probabilities at the Beijing and Xinglong stations, respectively, in April 2006. The analysis of the spatial distribution of the aerosol optical depth and the wind field reanalysis data showed that the long-range dust aerosol transport from Takla-Makan desert to North China Plain (NCP) was observed in April 2006. The aerosol radiative forcings at the top and bottom of the atmosphere are calculated for the period of dust haze propagation on the territory of China. During intense transports of dust aerosol to the Beijing region, the efficiency of the aerosol radiative forcing is shown to be 85 W/m 2 at the top of the atmosphere and 135–140 W/m 2 at the bottom of the atmosphere. Using the wind field reanalysis data, aerosol optical depth satellite monitoring data, and retrievals of the optical and microphysical characteristics of the tropospheric aerosol, we estimated the dust aerosol mass flux from Takla-Makan Desert to NCP (∼1.5 ton/s) in April 2006 and the daily total dust aerosol mass transport (∼1.5 million tons).