Aerosols have significant and complex impacts on regional climate in East Asia. Cloud‐aerosol‐precipitation interactions (CAPI) remain most challenging in climate studies. The quantitative understanding of CAPI requires good knowledge of aerosols, ranging from their formation, composition, transport, and their radiative, hygroscopic, and microphysical properties. A comprehensive review is presented here centered on the CAPI based chiefly, but not limited to, publications in the special section named EAST‐AIRcpc concerning (1) observations of aerosol loading and properties, (2) relationships between aerosols and meteorological variables affecting CAPI, (3) mechanisms behind CAPI, and (4) quantification of CAPI and their impact on climate. Heavy aerosol loading in East Asia has significant radiative effects by reducing surface radiation, increasing the air temperature, and lowering the boundary layer height. A key factor is aerosol absorption, which is particularly strong in central China. This absorption can have a wide range of impacts such as creating an imbalance of aerosol radiative forcing at the top and bottom of the atmosphere, leading to inconsistent retrievals of cloud variables from space‐borne and ground‐based instruments. Aerosol radiative forcing can delay or suppress the initiation and development of convective clouds whose microphysics can be further altered by the microphysical effect of aerosols. For the same cloud thickness, the likelihood of precipitation is influenced by aerosols: suppressing light rain and enhancing heavy rain, delaying but intensifying thunderstorms, and reducing the onset of isolated showers in most parts of China. Rainfall has become more inhomogeneous and more extreme in the heavily polluted urban regions.

Observations of surface direct solar radiation (DSR) and visibility, particulate matter with aerodynamic diameters less than 2.5 µm (PM_2.5), together with the aerosol optical thickness (AOT) taken from Moderate‐Resolution Imaging Spectroradiometer and Multiangle Imaging Spectroradiometer, were investigated to gain insight into the impact of aerosol pollution on surface solar radiation in China. The surface DSR decreased during 2004–2014 compared with 1993~2003 over eastern China, but no clear reduction was observed in remote regions with cleaner air. Significant correlations of visibility, PM_2.5, and regionally averaged AOT with the surface DSR over eastern China indicate that aerosol pollution greatly affects the energy available at the surface. The net loss of surface solar radiation also reduces the surface ground temperature over eastern China. However, the slope of the linear variation of the radiation with respect to atmospheric visibility is distinctly different at different stations, implying that the main aerosol type varies regionally. The largest slope value occurs at Zhengzhou and indicates that the aerosol absorption in central China is the highest, and lower slope values suggest relatively weakly absorbing types of aerosols at other locations. The spatial distribution of the linear slopes agrees well with the geographical distribution of the absorbing aerosols derived from the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations and Ozone Monitoring Instrument over China. The regional correlation between a larger slope value and higher absorbance properties of aerosols indicates that the net effects of aerosols on the surface solar energy and corresponding climatic effects are dependent on both aerosol amount and optical properties.

This study is concerned with the impacts of organic aerosols on cloud condensation nuclei (CCN) activity based on field measurements made at a suburban site in Northern China. The sensitivity of the estimated CCN number concentration (N_CCN) to both volume fraction of organic material (x_org) and aerosol oxidation level (using f₄₄, the fraction of m∕z 44 in aerosol organic material) are examined. A strong dependence of CCN number concentration (N_CCN) on the x_org and f₄₄ was noted. The sensitivity of N_CCN to volume fraction of organics increased with increasing x_org. The impacts of the aerosol particles oxidization or aging level on estimating N_CCN were also very significant. When the particles were mostly composed of organics (x_org > 60 %), the N_CCN at the supersaturation of 0.075 and 0.13 % was underestimated by 46 and 44 %, respectively, if aerosol particles were freshly emitted with primary organics (f₄₄ < 11 %); the underestimation decreased to 32 and 23 % at the corresponding supersaturations, however, if the particles were with more hygroscopic secondary organics (f₄₄ > 15 %). The N_CCN at the supersaturation of 0.76 % was underestimated by 11 and 4 %, respectively, at f₄₄ < 11 and f₄₄ > 15 %. However, for the particles composed of low organics (e.g., x_org < 40 %), the effect caused by the f₄₄ was quite insignificant both at high and low supersaturations. This is because the overall hygroscopicity of the particles is dominated by inorganics such as sulfate and nitrate, which are more hygroscopic than organic compounds. Our results indicated that it would decrease the uncertainties in estimating N_CCN and lead to a more accurate estimation of N_CCN to increase the proportion of secondary organics, especially when the composition of the aerosols is dominated by organics. The applicability of the CCN activation spectrum obtained at Xinzhou to the Xianghe site, about 400 km to the northeast of Xinzhou, was investigated, with the aim of further examining the sensitivity of N_CCN to aerosol type. Overall, the mean CCN efficiency spectrum derived from Xinzhou performs well at Xianghe when the supersaturation levels are > 0.2 % (overestimation of 2–4 %). However, N_CCN was overestimated by ∼ 20 % at supersaturation levels of < 0.1 %. This suggests that the overestimation is mainly due to the smaller proportion of aged and oxidized organic aerosols present at Xianghe compared to Xinzhou.