Experimental Investigation of Open Ocean and Coastal Aerosol (EICA)

• Applicants: Professor Dr. Jens Bange; Professorin Dr. Astrid Lampert; Dr. Birgit Wehner
• Subject Area: Atmospheric Science
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 532507805

The formation of aerosol particles from the gas phase contributes significantly to the global aerosol concentration. However, processes initiating and triggering this so-called new particle formation (NPF) are very complex. In particular the contribution of particles formed above the open ocean is unclear. The project EICA aims to distinguish between the remotely formed open-ocean nucleation and locally formed coastal nucleation, and to localize and characterize the different types of new particle formation events. Investigations are planned at the Global Atmosphere Watch site Mace Head at the West coast of Ireland. EICA deploys high resolution airborne measurements with two unmanned aerial vehicles (UAS), one measuring the particle number concentrations in different size classes, in particular very small, freshly formed particles with two condensation particle counters of different lower detection threshold diameter, the other focusing on turbulence parameters. The unique combination of the UAS ALADINA and MASC-V enables to localize regions with increased aerosol particle number concentrations > 5 nm on small scales and to obtain turbulence parameters in the same regions. Taking into account wind direction, tides and clouds, different types of new particle formation events are distinguished: open-ocean nucleation and coastal nucleation, new particle formation events that are detectable at ground and only aloft. For these cases, thermal stability, solar radiation and turbulence are analysed, as well as ground-based particle concentrations and aerosol precursor gases. The vertical and horizontal extent and the spatial variability of coastal new particle formation is investigated based on suitable flight patterns covering horizontal distances of several km and an altitude up to 1 km. Vertical profiling allows the detection of NPF events aloft, which makes it possible to quantify the contribution of NPF that may not be captured by ground-based observations. The impact of turbulence on triggering NPF and on particle transport will be quantified at this location by airborne small-scale in-situ measurements as well. The measurements quantify the contribution of the open-ocean nucleation for the coastal site. Ground-based measurements of aerosol properties and precursor gases from the research station Mace Head will be used to identify important contributors to NPF as well as favourable conditions for specific cases. Furthermore, these long-term measurements are needed to integrate the short-term airborne campaigns into the diurnal and seasonal development of aerosol properties. The interaction of clouds and NPF is addressed by a combination of in-situ measurements of NPF and remote sensing.

• DFG Programme: Research Grants
• International Connection: Finland, Ireland
• Co-Investigator: Dr. Roland Schrödner
• Cooperation Partners: Professor Dr. Michael Boy; Dr. Darius Ceburnis; Professor Dr. Colin D. O' Dowd