Assessing the Intensity of Marine Biogenic Influence on the Lower Atmosphere: An Insight into the Distribution of Marine Biogenic Aerosols over the Eastern China Seas

Marine biological activities make a non-negligible contributionto atmospheric aerosols, leading to potential impacts on the regionalatmospheric environment and climate. The eastern China seas are highlyproductive with significant emissions of biogenic substances, butthe spatiotemporal variations of marine biogenic aerosols are notwell known. Air mass exposure to chlorophyll a (AEC)can be used to indicate the influence of biogenic sources on the atmosphereto a certain degree. In this study, the 12 year (2009-2020)daily AEC were calculated over the eastern China seas, showing thespatial and seasonal patterns of marine biogenic influence intensitywhich were co-controlled by surface phytoplankton biomass and boundarylayer height. By combining the AEC values, relevant meteorologicalparameters, and extensive observations of a typical biogenic secondaryaerosol component, methanesulfonate (MSA), a parameterization schemefor MSA simulation was successfully constructed. This AEC-based approachwith observation constraints provides a new insight into the distributionof marine biogenic aerosols. Meanwhile, the wintertime air mass retentionover land exhibited a significant decrease, showing a decadal weakeningtrend of terrestrial transport, which is probably related to the weakeningof the East Asian winter monsoon. Thus, marine biogenic aerosols mayplay an increasingly important role in the studied region. Marine biogenic aerosols are climaticallyimportant butnot well simulated by models currently. This study presents an effectiveapproach to infer the spatiotemporal variations of marine biogenicaerosols over the eastern China seas in the context of changing terrestrialtransport.