Vertical profiles of cloud condensation nuclei number concentration and its empirical estimate from aerosol optical properties over the North China Plain

Abstract. To better understand the characteristics of aerosol activation ability and optical properties, a comprehensive airborne campaign was conducted over North China Plain (NCP) from 8 May to 11 June 2016. Vertical profiles cloud condensation nuclei (CCN) number concentration (NCCN) properties were measured simultaneously. Seventy-two-hour air mass back trajectories show that during campaign, measurement region mainly influenced by masses northwest southeast. Air sources, temperature structure, anthropogenic emissions, terrain distribution are factors influencing NCCN profiles. Cloud spectra suggest activate into CCN is stronger in southeasterly than northwesterly free atmosphere near surface. distributions scattering Ångström exponent (SAE) indicate aerosols surface originate primary emissions consisting more fine particles. The long-distance transport decreases SAE makes it vary troposphere parameterize NCCN, equation NCCN=10β⋅σγ used fit relationship between coefficient (σ) at 450 nm. fitting parameters β γ have linear relationships with SAE. Empirical estimates 0.7 % water vapor supersaturation (SS) thus retrieved for two masses: NCCN=10-0.22⋅SAE+2.39⋅σ0.30⋅SAE+0.29 NCCN=10-0.07⋅SAE+2.29⋅σ0.14⋅SAE+0.28 masses. estimated SS agrees measured, although performance differs low high concentrations results highlight important impact sources on empirical estimate properties.