Sea spray as an obscured source for marine cloud nuclei

It has been suggested that the sea spray aerosol (SSA) contributes a small fraction to cloud condensation nuclei (CCN) in global ocean, due to the low number concentration of SSA. However, the SSA number concentration was poorly constrained and often extrapolated from supermicron size distribution. Here the authors analyse the long-term observations of concentrations and compositions of aerosols in the Northeast Atlantic. They derive the submicron SSA number size distribution from ambient by combining hygroscopicity growth measurement and aerosol number size distribution. The results show that the number concentration of submicron SSA has been greatly underestimated and the SSA contributes significantly to the marine CCN budget, exceeding previous estimates by up to 500% at moderated marine cloud supersaturations. Given the impact of marine clouds on the Earth’s radiative budget, accounting for submicron SSA is essential to better constrain the aerosol-cloud interaction and future climate.

Reference: Xu, W., Ovadnevaite, J., Fossum, K. N., et al., (2022). Sea spray as an obscured source for marine cloud nuclei. Nature Geoscience, 15, 282-286. https://doi.org/10.1038/s41561-022-00917-2.