Atmospheric circulation drives major marine isoprene emission

The air-sea interface represented by the sea surface microlayer (SML) is of paramount importance in the global material exchange between ocean and atmosphere. The isoprene stands out as one of the most critical trace gases in air-sea gas interchange, offering valuable insights into the physical processes within the global ocean and atmosphere trace gases exchange. Utilizing our newly released 20-year high resolution dataset of global marine isoprene emissions, we have revealed the large-scale atmospheric circulation patterns that determine SML isoprene emissions and examined the impacts of local meteorological conditions on the SML emission over periods ranging from days to weeks. The development of the Rossby wave pattern controls the changes in surface winds, surface wind stress, the depth of the mixed layer and SST, which leads to the variation of the production and emission of the isoprene. As solar radiation increases, along with SST increase, weakened surface wind stress, and thinning of the mixed layer, isoprene is produced and stored in the SML. Consequently, as large-scale atmospheric circulation anomaly pattern develops and surface winds are strengthened, isoprene in the SML is emitted into the atmosphere. The results of this study emphasize the importance of large-scale atmospheric circulation patterns on the air-sea material exchange on the day-to-day time scale. Our air-sea exchange mechanism lays a theoretical framework for other biogenic trace gases and their intraseasonal variations, which helps to determine peaks in marine emissions and their subsequent impacts on regional marine atmospheric chemistry, particularly the formation of secondary organic aerosols and their role in cloud formation and climate regulation.