The topic of this proposal is the natural marine aerosol, which is of paramount importance at the global scale and influences the Earth’s radiative budget and the biogeochemical cycles. New particle formation dominates the atmospheric aerosol number budgets and most of these particles are formed by nucleation of marine biogenic vapours. MANU (Marine Aerosol NUcleations) aims to directly identify the spontaneous creation of new nanometer-sized particles in the open ocean marine atmosphere and to understand the physical and chemical transformations occurring in them once formed. MANU will (1) obtain the spatial variability of new particle formation (NPF) events in different open ocean areas, (2) elucidate the chemical composition of NPF events, (3) associate NPF events with biological processes and (4) interpret how NPF events affect the existing aerosol and its overall Cloud Condensation Nuclei (CCN) population. The approach involves state-of-the-art mass spectrometry measurements including ATOFMS, HR-ToF-MS and Api-ToF/MS during a Southern Ocean research cruise (Hesperides, 2014) and at the Mace Head research station (Ireland, 2015). The expected outcome of this Marie Curie action is to contribute to a significant step in the career of the promising European researcher such as the candidate, specifically adding missing complementary research competencies at an advanced level of new particle formation events measurements. Additional benefits to the European knowledge-based economy and society will also come from the important return phase of the project, where the experience and the knowledge acquired as well as the contact-network built up outside Europe will be shared. This proposal is multidisciplinary because two institutions with different backgrounds (outgoing: atmospheric chemistry; return: marine biology) aims to tackle the interdisciplinary research topic of open ocean NPF events while transferring knowledge to the candidate and the public.