640 / 2024-09-18 19:10:32

Different physiochemical properties and mixing state of atmospheric particles collected over South China Sea and western Pacific

Marine aerosols,Single particle analysis,Mixing state

Session 25 - IGAC-SOLAS: Chemistry and physics at surface ocean and lower atmosphere

Marine aerosols play important roles in the global radiation balance and biogeochemistry. However, the physiochemical properties of atmospheric particles have not been well-understood at single-particle level, especially when related to diverse sources and processes. Based on single particle analysis, we compared the elemental composition and mixing state of atmospheric particles collected over South China Sea (SCS) and western Pacific (WP) in this study. The two areas have similar dominant particle types. Sea salt particles have higher contributions over WP, while organic particles and sulfur-containing particles are more frequently over SCS. During the study periods, K-rich particles and dust particles are only found over SCS. The particle chemical composition over marine atmosphere are impacted by marine emission and secondary processes, with a decreased influence of anthropogenic and land emission for the open ocean. The diverse sources result in more variable elemental diversities and a lower mixing state index of aerosols over SCS, while aerosols over WP have a more stable elemental diversity and a higher mixing state index due to relatively simple sources. In the marine atmosphere, as the main source, the increased contribution of marine emission lead to internal mixing. However, secondary processes and adding land primary particles move the aerosols to external mixing state. This combination of the unique single particle analysis and mixing state analysis provides a basis to study marine aerosols influenced by different sources and processes for better understanding in their impacts on climate.