Investigating marine driven new particle formation during the SOPHYAC-light campaign

The Antarctic region is a large component of the global climate system.  While it is largely underrepresented in climate models due to the scarcity of in-situ data, the interactions between processes occurring mid- and high-latitude are even less investigated. Understanding the processes between the atmosphere, the ocean laying within the polar front is critical to assert the relevance of climate models and improve future climate predictions. 

The SOPHYAC-light (Responses of the Southern Ocean PHYtoplankton to climate changes, feedback to the Atmosphere -impact of Light) took place onboard of the research vessel Marion Dufresne during the Obs’Austral campaign 2025 between December 24^th 2024 and February 5^th 2025. Air-sea interaction process studies were performed using two Air-Sea Interface Tanks (ASIT, Sellegri et al. 2023) in the aim of quantifying realistic air-sea fluxes and their relation to seawater biochemical properties, as well as the impact of UV light on these processes.  The twotanks, one as a control and the other UV shielded, were filled with 1 m³ of seawater each at 7 different locations of the Southern Ocean, between sub-tropical and sub-Antarctic regions along the ship track.  The incubation time varied between 4 and 6 days with coordinated water sample coupled with continuous atmospheric sampling within the head space of the two ASITS, with measurements of chemical, physical & biological parameters. The atmospheric measurements were focused on the investigation of new particle formation, encompassing three mass spectrometers for the characterization of gas phase precursors of aerosols and nanoparticle size distribution. A first overview of the SOPHYAC results related to new particle formation purely driven by the marine environment and ecosystem across the tropical / polar transect will be presented at the conference.