[A-CG45] Biogeochemical linkages between the surface ocean and atmosphere

[ACG45-P03] Diagnosis of sea-spray aerosol concentrations in the marine boundary layer using "Reynolds number"

*Takuma Miyakawa¹, Fumikazu Taketani¹, Masayuki Takigawa¹, Yutaka Tobo^2,3, Takeshi Kinase¹, Yugo Kanaya¹ (1.Japan Agency for Marine-Earth Science and Technology, 2.National Institute for Polar Research, 3.The Graduate University for Advanced Studies, SOKENDAI)

Keywords:SSA, MBL, SSSF, Southern Ocean, Northwestern Pacific Ocean, Reynolds number

Maritime aerosol particles play an important role in the modulation of the Earth’s radiative balance through the cloud formation. Since the emission flux of sea-spray aerosol (SSA) particles has not well been characterized so far because of the technological difficulties, most of previous studies have investigated the relationship between the aerosol concentrations and wind speed at 10 m height above the sea level both of which were obtained in the in-situ observations in the marine boundary layer (MBL). Wave breaking to produce SSA from the ocean surface has related to the whitecap fraction of the ocean surface. In the research area of ocean physics, it is well known that Reynolds number, Re (Zhao and Toba, 2001) rather than wind speed can well account for the variation of the whitecap fraction. The parameterization of the size resolved sea-spray aerosols, "OSSA-SSSF", was developed by Ovadnevaite et al. (2014). In this study, we analyzed the aerosol particle number size distributions and sea-salt aerosol concentrations in the MBL in terms of Re and OSSA-SSSF. In the presentation, we report the results from the research cruises of the R/V Mirai (MR16-09 and MR21-01) over the Pacific Ocean sector of the Southern Ocean and Northwestern Pacific Ocean. In the presentation, we will discuss the derived findings that OSSA-SSSF was an efficient parameterization to predict the concentrations of SSA in the MBL, that the SSA concentrations in the MBL were strongly affected not only by Re but also the surface mixing layer height, and that SSA cannot fully account for the cloud condensation nuclei over the Southern Ocean.