New Insights Into Nighttime Marine Sulfur and Nitrogen Chemistry and Related New Particle Formation Using the CLEPS Model

Abstract Nucleation of aerosol particles is the main source of cloud condensation nuclei over most oceans. Dimethyl sulfide (DMS) is the volatile gas released by the marine biota suspected to drive nucleation over the ocean and it is often the only marine nucleation precursor gas implemented in atmospheric models. Using deck borne air‐sea enclosures, previous work reported nighttime nucleation related to nitrate ions (NO 3 − ) and presumed potential marine nitrogen biological‐emitted precursors. In the present study, the enclosure's headspace and seawater chemistry are simulated using CLEPS, a multiphase atmospheric chemistry model. Simulations first allowed to relate the aqueous DMS production rate to marine biology and indicated that any increases in ozone concentrations that would occur in the future should deplete DMS seawater emissions via enhanced aqueous reactivity. We then also show that nighttime production of nitric oxide (NO), expressed as a function of DMS production rate, was proficient to retrieve a profile of nitric acid (HNO 3 ) matching the observed NO 3 − temporal variability. Simulated HNO 3 concentrations were eventually used, together with measured particle formation rates, to derive a new nucleation parameterization. However, while these results demonstrate the value of CLEPS in interpreting in situ measurements, they also suggest that developments aimed at optimizing the model for describing ocean‐atmosphere exchanges of other important VOCs such as isoprene and monoterpenes and the halogen chemistry should be carried out in the future to enable more in‐depth studies of this specific environment.