The regional aerosol in eastern central china and its cloud microphysical and optical properties of haze at high relative humidities

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Large areas of China suffer from heavy air pollution caused by the strong economic growth in the last two decades. Especially, regions such as the Pearl River Delta in Southern China and the eastern central region around Beijing underlie haze layers clearly visible from satellite observations. The reduced visibility and the large optical depth caused from high aerosol concentrations are strongly dependent on the ability to take up water (hygroscopicity). At relative humidities between 90 and 99%, the aerosol particles grow exponentionally. The hygroscopic behavior at relative humidities close to 100% is strongly linked to the particles ability to grow into cloud droplets at supersaturation. The strong anthropogenic emission of aerosol particles implies a change of the cloud droplet size distribution which increases the cloud albedo. This indirect aerosol effect leads to a general cooling of the atmosphere and is one of the most uncertain parameters with respect to global change. Especially in China, this impact is supposed to be very large, because of the high concentration of anthropogenically emitted particles. Within this project, the characterization of the particle number size distribution, the particle optical properties, their hygroscopic properties at high RH below supersaturation, their cloud nucleating properties above supersaturation, their subsequent activation dynamic growth, and their chemically size-resolved properties are planned to be characterized.