CALIPSO-based morphology change and hygroscopic growth of East Asian dust

Natural mineral dust and intensive anthropogenic emissions and its complex mixing processes during transport result in great impacts on regional environmental quality and climate in East Asia. However, the morphology change and hygroscopicity of East Asian dust particles owing to coating anthropogenic pollutants are still statistically poorly understood. In this study, the statistically significant morphology change and hygroscopic growth of East Asian dust particles in a real atmosphere were firstly evaluated by combining CALIOP lidar measurements and relative humidity (RH) derived from the MERRA-2 during the past ten years (2007-2016). Our statistical results indicate that the optical properties of East Asian dust aerosol have significant region inhomogeneity and trend to be smaller in particle size and regular in shape during transport away from the source area. The dust particle irregularities and extinction coefficient were significantly decreasing and increasing with increasing ambient RH, respectively.The irregularity declining rate of mineral dust tended to slow down from source region (-0.89) to transport region with intensive anthropogenic emissions (-0.14). The strong positive linear correlation between dust extinction coefficient and relative humidity demonstrate the dust aerosol’s hygroscopic growth. It is attributed as a result of possible saline component and coating anthropogenic pollutants. The stronger hygroscopic growth of dust aerosol in the lower atmosphere has also been found. These results improve our understanding on the hygroscopicity of East Asian dust aerosol. Dust particles coating with anthropogenic pollution have a great ability of acting cloud condensation nucleus (CCN) in the lower atmosphere, which will affect the cloud microphysical processes and even climate effect.