CAPEKCHEM

CAPE-K: Aerosol composition and precursors

4 October 2024 - 30 May 2025

Lead Scientist: Branka Miljevic

Observatory: AMF (ARM Mobile Facility 2) - KCG

Production of aerosol particles in the marine environment occurs primarily via two pathways: 1) wave breaking and bubble bursting, which results in primary particles composed mainly of sea salt and biogenic organic matter, and 2) sea-air exchange of gaseous compounds produced by marine biota (phytoplankton, algae), in particular dimethyl sulphide, and the subsequent secondary particle formation from oxidation of these species. Aerosols resulting from these two different sources will have different composition, size and number concentration, and, therefore, different ability to act as cloud condensation nuclei. Knowing the spatial and temporal impact of these sources on the overall aerosol populations and physicochemical properties is vital in attributing climate impacts to biogenic sources versus wind and bubble bursting produced sea-salt aerosol. Cape_k_Chem seeks to expand the scope of measurements being conducted during the Cape-k period to include aerosol size-resolved chemical composition (1), aerosols precursor vapours (2), and new particle formation (3), with the aim to enhance our understanding of processes driving aerosol formation, growth to seeds for cloud droplets, and overall aerosol populations over the Southern Ocean.  The proposed additional measurements will be achieved by deploying the following instruments: (1) High resolution Time of Flight Aerosol Mass Spectrometer (HR ToF-AMS), (2) Nitrate-Chemical Ionisation Mass Spectrometer (Nitrate-CIMS), and (3) Neutral cluster and Air Ion Spectrometer (NAIS), with all three being deployed at the kennaook/Cape Grim station for the first time.