[A-AS09] Atmospheric Chemistry

[AAS09-P14] Continental impact on submicron aerosol concentrations in the marine boundary layer from an research cruise of R/V Mirai over the Northwestern Pacific Ocean

*Takuma Miyakawa¹, Takeshi Kinase¹, Minako Kurisu¹, Kyoko Taniguchi¹, Masaki Katsumata¹, Fumikazu Taketani¹, Yugo Kanaya¹ (1.Japan Agency for Marine-Earth Science and Technology)

Keywords:Aerosol, Shipborne observation, Northwestern Pacific Ocean, Continental impact, Long-range transport

Fine aerosol particles in the marine boundary layer (MBL) plays significant roles in the aerosol-cloud interactions through the cloud formation over the ocean. In the northern midlatitude region, especially East Chin Sea and northwestern Pacific Ocean, not only sea-spraying sources but also long-range transport from continental sources can enhance the aerosol concentrations and modulate the aerosol-cloud interactions (e.g., Koike et al., 2012). Intensive observations of fine aerosol particle physical and chemical parameters (size distributions and compositions) in the MBL over the Northwestern Pacific Ocean were performed in the winter–early spring of 2021 during the research cruise MR21-01 of R/V Mirai. Size-resolved chemical/elemental compositions of aerosols were measured using a high-volume air sampler (HV-120SL, Kimoto Electric) with a cascade impactor (TE-236, Tisch Environmental) and the following chemical/elemental analyses based on IC and ICP-MS (i.e., offline method). Submicron aerosol elemental compositions were measured using a semi-online automated XRF-based aerosol elemental composition analyzer (PX-375, HORIBA, Miyakawa et al., 2023). The PX-375 measurements were evaluated by the offline method, indicating that the major targeted elements such as iron, chlorine (of sea-salt), and sulfur (of sulfate) were accurately measured by the PX-375 within the uncertainties derived from the differences in the size cut of aerosol sampling between PX-375 and the offline method. R/V cruised the subtropical region (25–30°N) during the latter part of the cruise, and then encountered the air masses with the substantially enhanced concentrations of submicron aerosols. Backward trajectories and satellite data suggested that the possible impacts of the long-range transport of air masses from the anthropogenic sources over the central China and the biomass burning in the Southeast Asia (i.e., Indochina peninsula) can account for the event. In the presentation, temporal variations in the elemental compositions in this event are discussed in terms of the comparison with combustion tracer compounds such as carbon monoxide (48-iTLE, Thermo Fisher Scientific) and black carbon (SP2, Droplet Measurement Technologies).

References:
Koike, M., et al. (2012), J. Geophys. Res., https://doi.org/10.1029/2011JD017324
Miyakawa, T., et al. (2023), Atmos. Chem. Phys., https://doi.org/10.5194/acp-23-14609-2023