Data of "Cloud Condensation Nuclei and the Contribution of New Particle Formation in the Yangtze River Delta of Eastern China" -version1

Cloud condensation nuclei (CCN) serve as a critical link between aerosols and clouds, with new particle formation (NPF) recognized as a major source of CCN. However, the quantitative contribution of NPF to CCN remains highly variable and insufficiently constrained by in-situ observations. To address this gap, two-year synchronized observations of CCN, particle number size distribution (PNSD), and chemical composition were conducted in an urban area of eastern China. The average CCN concentration (NCCN) was 2220 ± 1050, 3510 ± 1500, 4050 ± 1640, and 4400 ± 1740 cm⁻³ at 0.2%, 0.4%, 0.6%, and 0.8% supersaturation, respectively. Comparisons between observed and calculated NCCN derived from PNSD and aerosol hygroscopicity revealed uncertainties in representing the hygroscopicity of organic-rich and NPF-origin particles. NCCN exhibited distinct diurnal variations, with concurrent anthropogenic emissions obscuring the apparent NPF contribution to CCN. By distinguishing CCN into primary and secondary components and focusing on secondary CCN, NPF-related increases were estimated at 54-71% across supersaturations of 0.2-0.8%, substantially higher than conventional estimates. Results from the complementary survival probability (SP) approach further confirmed enhanced CCN formation efficiency under warm, low-pollution conditions, consistent with higher formation rates and SP. As air quality management continues to reduce PM2.5 mass concentrations, the organic fraction and NPF frequency are likely to increase. These trends underscore the growing importance of NPF in CCN production and the necessity for coordinated, long-term observations of CCN and NPF to improve constraints on aerosol–cloud interactions and climate effects.