Marine aerosol size distributions in the springtime over China adjacent seas: Fid-Bau Portal

Marine aerosol size distributions in the springtime over China adjacent seas

Lin, Peng / Hu, Min / Wu, Zhijun / Niu, Yuwen / Zhu, Tong

AbstractSize distributions and particle number concentrations of atmospheric aerosols in the size (diameter) range from 15nm to $10 μ m$ were measured on board of a research ship during three cruises in China adjacent seas. The total particle number concentrations were in average around $4000 {cm}^{- 3}$ in Yellow Sea, $2000 {cm}^{- 3}$ in East China Sea and $1000 {cm}^{- 3}$ in South China Sea. The observed size distributions were fitted with two or three log-normal modes and the data were classified according to time, regions and calculated air mass back-trajectories. The size distribution spectra of air masses of polluted continental origin as their back-trajectories showed were characterized by single mode with total number concentrations between 1000 and $10 000 {cm}^{- 3}$ . The size distributions in marine air masses showed dual mode characteristics, one maximum at 40–60nm and the other at 160–190nm with total number concentrations below $1000 {cm}^{- 3}$ . This type of dual mode was more pronounced at longer residence time of the air masses over the ocean. The burst of ultra-fine (UF) particles and the consequent growth processes were observed twice in Yellow Sea and possible reasons leading to these events are discussed. The particle growth rate (GR) was $3.4 \pm 0.9$ and $3.5 \pm 1.6 {nmh}^{- 1}$ , respectively (95% confidence interval), indicating that the UF particles can grow to cloud condensation nuclei (CCN) within the next 1–2 days.