Final Report Summary - MANU (Marine Aerosol NUcleations) MANU (Marine Aerosol NUcleation) studied the natural marine aerosol, which is of paramount importance at the global scale and influences the Earth’s radiative budget and the biogeochemical cycles. MANU aimed 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. The project took advantage of fixed (monitoring station) and mobile (research vessel) sites over the Antarctic and Arctic, perhaps one the least studied atmospheric marine regions.Climate warming affects the development and distribution of sea ice, but at present the evidence of polar ecosystem feedbacks on climate through changes in the atmosphere is sparse. By means of synergistic atmospheric and oceanic measurements in the Southern Ocean near Antarctica, we presented evidence that the microbiota of sea ice and sea ice-influenced ocean are a previously unknown significant source of atmospheric organic nitrogen, including low molecular weight alkyl-amines. Given the keystone role of nitrogen compounds in aerosol formation, growth and neutralization, our findings call for greater diversity in modelling efforts linking the marine ecosystem to aerosol-mediated climate effects in the Southern Ocean. Atmospheric new particle formation and growth significantly influences climate by supplying new seeds for cloud condensation and brightness. Currently, there is a lack of understanding of whether and how marine biota emissions affect aerosol-cloud-climate interactions in polar regions. Given the relationships between aerosol new particle formation and sea ice regions found in Antarctica, we studied longer datasets available in the Arctic regions. Arctic aerosols datasets are currently available around the Aerosol EU network of aerosol sampling stations, favoured over Antarctica for obvious reasons of proximity. Air mass trajectory analysis and atmospheric nitrogen and sulphur tracers linked frequent nucleation events to biogenic precursors released by open water and melting sea ice regions. The occurrence of such events across a full decade was anti-correlated with sea ice extent. MANU was able to boost multidisciplinary polar ocean-atmosphere science and setting the ground for conceiving and carrying out new laboratory and field studies thanks to the employment of ultra-sensitive, state-of-the-art technologies for aerosol measurements. Related documents final1-periodic-report-submit-manu.pdf
