Arctic Sea Ice Melting Controls Sea Spray Aerosol Production

The loss of Arctic Sea ice enlarges the ocean water surface exposed to wind speed, increasing the emissions of sea spray aerosols (SSAs). Given the unique evolution of upper ocean salinity waters and ice-associated ecosystems, it is crucial to improve Arctic-specific SSA parametrizations to represent the currently poorly understood feedback processes. Here, by using Arctic ship-borne in situ aerosol tank laboratory experiments, we study SSA produced from open ocean, open leads, and melt ponds. We find a complex nonlinear, yet unresolved variation in SSA production associated with salinity and organic composition. Specifically, we find that melt ponds drastically reduce SSA production, whereas ice algal microgels may enhance it. During the summer 2017 cruise (research vessel Araon), we also carried out aerosol ambient measurements across the Chukchi and East Siberian Seas. Size resolved ambient particle number concentrations reveal at least 17% and 42% of ambient number aerosol concentrations (N_10-300 nm and N_100-300 nm, respectively) are possibly attributable to SSA. Our results may help modeling experiments using SSA parametrization currently suffering from large uncertainty for constraining the sea spray emission fluxes from leads, melt ponds, and salinity gradients encountered in the Arctic Ocean.