Production and growth of new particles during two cruise campaigns in the marginal seas of China

Abstract. In this paper, we investigated production and growth of new particles in the marine atmosphere during two cruise campaigns in China Seas using a Fast Mobility Particle Sizer. Only eight new particle formation (NPF) events (> 30 min) occurred on 5 days out of 31 sampling days, and the subsequent growth of new particles was observed only in five events. Apparent formation rates of new particles (in the range of 5.6–30 nm) varied from 0.3 to 15.2 particles cm⁻³ s⁻¹ in eight events, and growth rates ranged from 2.5 to 10 nm h⁻¹ in five NPF events. Modeling results simulated by US EPA Community Multi-scale Air Quality Model (CMAQ) showed that ammonium nitrate (NH₄NO₃) was newly formed in the atmosphere over the corresponding sea zone during 2 out of 5 events, in which new particles partially or mostly grew over 50 nm. However, in the remaining three events, new particles cannot grow over 30 nm, and the modeling results showed that no NH₄NO₃ was newly formed in the corresponding marine atmosphere. Modeling results also showed that formation of secondary organics occurred through all new particle growth periods. Difference between the two types of new particle growth patterns suggested that a combination of ammonium nitrate and organics newly formed likely contributed to the growth of new particles from 30 nm to larger size. However, the findings were obtained from the limited data, and the simulations of CMAQ also suffered from several weaknesses such as only having three size bins for different particles, lack of marine aerosol precursors, etc. More future studies are thereby needed for confirmation.