ASREN

Aerosol sources in the remote North Atlantic

1 June 2025 - 28 February 2026

Lead Scientist: Wendell Walters

Observatory: ENA

Aerosols play a crucial role in atmospheric processes, significantly impacting climate dynamics, cloud formation, and precipitation patterns. However, uncertainties persist, particularly in remote marine environments such as the Eastern North Atlantic, where interactions between aerosols and low-cloud systems are complex and poorly understood. This project aims to address these uncertainties by focusing on the chemical formation and sources of key aerosol components, including non-sea salt sulfate (nss-pSO4), ammonium (pNH4), and reduced organic nitrogen (pRON). These aerosol components are known to influence aerosol nucleation, condensation, and cloud properties, yet their origins and contributions remain poorly constrained. By investigating the seasonal chemical processes governing their formation and the sources driving their presence in the atmosphere, we seek to enhance our understanding of aerosol burden and its implications for climate dynamics in the Eastern North Atlantic region.

Here, we propose a comprehensive investigation to quantify the chemical formation pathways and source apportionment of nss-pSO4, pNH4, and pRON in the Eastern North Atlantic. Our primary objective is to elucidate the origins and contributions of these key components to aerosol new particle formation and growth, with a specific emphasis on distinguishing between anthropogenic and natural emissions. Through detailed chemical and isotopic analysis of size-segregated aerosols and precursor gases, we aim to advance our understanding of aerosol chemistry in the Eastern North Atlantic and its ramifications for atmospheric processes and climate dynamics. Our specific objectives include: (1) Quantify the nss-pSO4 chemical formation pathways to better constrain its atmospheric burden; (2) Conduct source apportionment of nss-pSO4 with a focus on natural vs anthropogenic origins; (3) Evaluate the role and sources of reduced nitrogen on aerosol formation. By focusing on these pivotal marine aerosol components that significantly influence nucleation and serve as cloud condensation nuclei, we aim to augment our understanding of their atmospheric burden and their links to climate dynamics.

To achieve our objectives, we will conduct field measurements at the U.S. Department of Energy Eastern North Atlantic (ENA) atmospheric observatory on Graciosa Island, Azores, Portugal. Size-segregated aerosols and precursor gases will be collected for comprehensive chemical and stable isotopic analyses. These analyses will provide insights into the sources and formation pathways of key aerosol components. Additionally, we will utilize comprehensive meteorological and aerosol composition data from the ENA observatory to establish connections between aerosol chemistry, formation processes, and source attribution to key aerosol properties, including cloud condensation nuclei concentrations. This integrated approach will enable us to unravel the complex interactions driving aerosol dynamics in the Eastern North Atlantic region.