Retrieval of Atmospheric Fine Particulate Density Based on Merging Particle Size Distribution Measurements: Multi‐instrument Observation and Quality Control at Shouxian

Abstract

AbstractDensity of fine mode particles is an important physical parameter. However, its measurement and validation in the actual atmosphere are still difficult. In this study, the measurements at Shouxian, Anhui province, China (32.56°N, 116.78°E, elevation 22.7 m) in winter, are used for density retrieval and quality control. The effective density and number size distribution of fine mode aerosol can be obtained in real time, by using the scanning mobility particle sizer and aerodynamic particle sizer. During the experiment, the average density is about 1.66 ± 0.15 g/cm3 with the uncertainty of 0.19 g/cm3 calculated from the residuals in the overlap region of scanning mobility and aerodynamic particle sizers. A multi‐instrument measurement and quality control scheme is proposed to identify large measurement uncertainties. The extinction and scattering coefficients calculated from the merged fine particle number size distributions by Mie theory are comparable with the measurements from cavity‐enhanced albedometer. The differences between the calculated and observed scattering and extinction coefficients are less than 2%. Meanwhile, the deduced aerosol complex refractive index n and k are obtained by minimizing the sum of squared residuals of extinction and scattering coefficients and comparable with the values retrieved from the Sun‐sky radiometer CE318 measurements. The correlation coefficient on n is 0.72. However, the correlation on k is not optimized, explained by the influence of anthropogenic aerosol particles with strong absorption near ground and the poor accuracy of k. Compared with independent observations, a good agreement between the optical parameters is also obtained.