A study on the Seasonal Variability of Wave-generated Sea-spray Aerosol over an Estuarine Fjord

Abstract

Involved in direct and indirect radiative effects over marine regions, sea spray aerosols are important constituents of atmospheric aerosols. This makes understanding the annual variability in sea-air transfer of aerosol particles essential. However, due to the difficulties of working in the marine environment, continuous records of sea spray aerosol are rare. This study presents one of the few seasonal time-series records of sea spray aerosol. Bulk surface seawater was sourced fortnightly from the Bedford Basin, a fjord in Atlantic Canada. The water was transferred into a plunging-wave tank to produce aerosols through the generation of whitewater. Analysis of bulk seawater and resulting sea spray aerosol properties showed evidence of coupling between them. Changes observed in sea spray aerosol size and concentration over the year were strongly influenced by oceanic processes in the fjord, namely surface biological productivity and vertical mixing. Likewise, the activation of liquid cloud droplets responded significantly to seasonal changes in the basin. This is evidence that variation in sea surface conditions need to be taken into consideration when discussing marine aerosol emissions and their role in cloud processes. The study is a fundamental step towards better understanding the relationship between the surface ocean and marine atmospheric aerosols.