Wave breaking in the Earth’s oceans constitutes the biggest natural source of atmospheric aerosol particles globally. Their large abundance makes sea spray aerosols a key species in the climate system, as they interact with solar radiation and act as seeds for cloud droplets. Consequently, they have gained great scientific attention. One conundrum, however, has remained unresolved: Fresh sea spray aerosols as generated in the laboratory have different physicochemical properties than aerosol particles observed in the marine boundary layer. This observational gap hinders full understanding of 1) sea spray aerosol formation and 2) sea spray aerosol climate effects. The aim of this project is to answer this question experimentally.
We plan to simultaneously, in-situ, and in real time measure the physicochemical properties of ambient aerosol particles in the marine boundary layer, and fresh sea spray aerosol generated in a mobile sea spray tank using directly sampled real ocean water, on cruises in the Atlantic Ocean. Aging of particles will be investigated with a flow tube reactor with which atmospheric oxidative processes can be simulated. Particle chemical composition will be measured at unprecedented chemical and temporal resolution with a novel, state-of-the-art mass spectrometric technique. The data will provide the basis for improved parameterizations of sea spray aerosols in climate models.
Our first field campaign will be in summer 2022 at the eastern North Atlantic (ENA) atmospheric observatory on the island of Graciosa (Azores, Portugal). We will join the AGENA campaign together with our collaborators from the US.