Chemical Composition of Ultrafine Sea Spray Aerosol during the Sea Spray Chemistry and Particle Evolution (SeaSCAPE) Experiment

Abstract:

Atmospheric aerosols have significant direct and indirect impacts on climate, but our understanding of the sources and composition of marine aerosol remains limited. The physical properties and atmospheric fate of sea spray aerosol depend on its chemical composition and are therefore related to the biochemical makeup of the seawater and the bubble bursting process. The composition of ultrafine (< 100 nm diameter) sea spray affects the critical diameter for activation to cloud droplets. This study presents online measurements of sea salt mass fractions in ultrafine sea spray aerosol during the Sea Spray Chemistry and Particle Evolution (SeaSCAPE) campaign held in the summer of 2019 at Scripps Institute of Oceanography. Primary sea spray aerosol was generated in a wave flume mesocosm with coastal water obtained from Scripps Pier in San Diego, CA. The composition measurements were performed using the Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS). Mass calibrations for Na⁺ and Cl^- were characterized to quantify the significant fraction of inorganic sea salt in ultrafine sea spray aerosol. Trends in fraction of these inorganics with respect to organic species will be discussed in the context of evolving biological activity during the measurements.