Quantified effect of seawater biogeochemistry on the temperature dependence of sea spray aerosol fluxes

Future change in sea surface temperature may influence climate via various air-sea feedbacks and pathways. In this study, we investigate the influence of surface seawater biogeochemical composition on the temperature dependence of sea spray number emission fluxes. Dependence of sea spray fluxes was investigated in different water masses (i.e. subantarctic, subtropical and frontal bloom) with contrasting biogeochemical properties across a temperature range from ambient (13&ndash;18 &deg;C) to 2 &deg;C, using seawater circulating in a plunging jet sea spray generator. We observed sea spray total concentration to increase significantly at temperatures below 8 &deg;C, with an average 4-fold increase at 2 &deg;C relative to initial concentration at ambient temperatures. This temperature dependence was more pronounced for smaller size sea spray particles (i.e. nucleation and Aitken modes). Moreover, temperature dependence varied with water mass type and so biogeochemical properties. While the sea spray flux at moderate temperatures (8&ndash;11 &deg;C) was highest in frontal bloom waters, the effect of low temperature on the sea spray flux was highest with subtropical seawaters. The temperature dependence of sea spray flux was also inversely proportional to the seawater cell abundance of the cyanobacterium Synechococcus, which facilitated parameterization of temperature dependence of sea spray emission fluxes as a function of Synechococcus for future implementation in modelling exercises.</p

Evidence of nitrate-based nighttime atmospheric nucleation driven by marine microorganisms in the South Pacific

9 pags. 3 figs.Our understanding of ocean-cloud interactions and their effect on climate lacks insight into a key pathway: do biogenic marine emissions form new particles in the open ocean atmosphere? Using measurements collected in ship-borne air-sea interface tanks deployed in the Southwestern Pacific Ocean, we identified new particle formation (NPF) during nighttime that was related to plankton community composition. We show that nitrate ions are the only species for which abundance could support NPF rates in our semicontrolled experiments. Nitrate ions also prevailed in the natural pristine marine atmosphere and were elevated under higher sub-10 nm particle concentrations. We hypothesize that these nucleation events were fueled by complex, short-term biogeochemical cycling involving the microbial loop. These findings suggest a new perspective with a previously unidentified role of nitrate of marine biogeochemical origin in aerosol nucleation.We acknowledge the support and expertise of the Officers and Crew of the R/V Tangaroa and National Institute of Water and Atmospheric Research (NIWA) Vessel Services. This research received funding from the European Research Council (ERC) under the Horizon 2020 research and innovation program (Sea2Cloud grant agreement number - 771369 and grant agreement number 101002728) and was supported by NIWA SSIF funding to the Ocean-Climate Interactions, and Flows and Productivity Programs. The support from the Academy of Finland (331207) and the German Academic Exchange Service (DAAD) is greatly appreciated.Peer reviewe

Biopolymer composition and surface activity in the surface waters in Eckernförde bay in summer 2018

During two crusies in June (AL510) and September (AL516) 2018, a data set (N=76) from the sea surface microlayer (SML) was compiled in Eckernförde Bay, Germany. SML samples were collected with the glass plate technique. Reference samples from the underlying water (ULW) at an approx. depth of 20cm were collected with the help of a bottle. Total and dissolved hydrolysable amino acids, combined carbohydrates and dissolved organic carbon were analyzed to describe surfactant dynamics (based on phase-sensitive AC voltammetry). Flow cytometry provided additional information on bacteria and phytoplankton community composition. This data set resolves dynamics on short temporal (diurnal sampling ) and local scales (within an area of 50km^2)

Meteorology at SML stations during Alkor cruises AL510 and AL516

During two crusies in June (AL510) and September (AL516) 2018, a data set (N=76) from the sea surface microlayer (SML) was compiled in Eckernförde Bay, Germany. SML samples were collected with the glass plate technique. Reference samples from the underlying water (ULW) at an approx. depth of 20cm were collected with the help of a bottle. Total and dissolved hydrolysable amino acids, combined carbohydrates and dissolved organic carbon were analyzed to describe surfactant dynamics (based on phase-sensitive AC voltammetry). Flow cytometry provided additional information on bacteria and phytoplankton community composition. This data set resolves dynamics on short temporal (diurnal sampling ) and local scales (within an area of 50km^2)

Hydrology at CTD stations during Alkor cruises AL510 and Al516

During two crusies in June (AL510) and September (AL516) 2018, a data set (N=76) from the sea surface microlayer (SML) was compiled in Eckernförde Bay, Germany. SML samples were collected with the glass plate technique. Reference samples from the underlying water (ULW) at an approx. depth of 20cm were collected with the help of a bottle. Total and dissolved hydrolysable amino acids, combined carbohydrates and dissolved organic carbon were analyzed to describe surfactant dynamics (based on phase-sensitive AC voltammetry). Flow cytometry provided additional information on bacteria and phytoplankton community composition. This data set resolves dynamics on short temporal (diurnal sampling ) and local scales (within an area of 50km^2)

Carbohydrates at SML stations during Alkor cruises AL510 and AL516

During two crusies in June (AL510) and September (AL516) 2018, a data set (N=76) from the sea surface microlayer (SML) was compiled in Eckernförde Bay, Germany. SML samples were collected with the glass plate technique. Reference samples from the underlying water (ULW) at an approx. depth of 20cm were collected with the help of a bottle. Total and dissolved hydrolysable amino acids, combined carbohydrates and dissolved organic carbon were analyzed to describe surfactant dynamics (based on phase-sensitive AC voltammetry). Flow cytometry provided additional information on bacteria and phytoplankton community composition. This data set resolves dynamics on short temporal (diurnal sampling ) and local scales (within an area of 50km^2)

Amino acids at SML stations during Alkor cruises AL510 and AL516

During two crusies in June (AL510) and September (AL516) 2018, a data set (N=76) from the sea surface microlayer (SML) was compiled in Eckernförde Bay, Germany. SML samples were collected with the glass plate technique. Reference samples from the underlying water (ULW) at an approx. depth of 20cm were collected with the help of a bottle. Total and dissolved hydrolysable amino acids, combined carbohydrates and dissolved organic carbon were analyzed to describe surfactant dynamics (based on phase-sensitive AC voltammetry). Flow cytometry provided additional information on bacteria and phytoplankton community composition. This data set resolves dynamics on short temporal (diurnal sampling ) and local scales (within an area of 50km^2)

Microbial and molecular description of the sea surface microlayer off Mauritania during POSEIDON cruise POS519, Jan/Feb 2018

Data were collected off Mauritania in January and February 2018 from board the RV Poseidon inside and outside a recently upwelled filament propagating offshore. To sample the Sea Surface Microlayer (SML), a depth of approx. 0.5mm, we used a screen sampler (Garrett 1965). As reference, samples from the underlying water (ULW) from the ships inlet at 2m depth were collected. Data provide information about the molecular and microbial composition of the SML including amino acids, carbohydrates, and flow cytometry data. The concentration of surface active substances was assessed by AC phase sensitive voltammetry and are expressed as Triton-X equivalents. Sea surface temperature, salinity and further weather data were obtained from the on-board ships weather station

Bulk organic matter concentrations and microorganisms abundance at SML stations during Alkor cruises AL510 and AL516

During two crusies in June (AL510) and September (AL516) 2018, a data set (N=76) from the sea surface microlayer (SML) was compiled in Eckernförde Bay, Germany. SML samples were collected with the glass plate technique. Reference samples from the underlying water (ULW) at an approx. depth of 20cm were collected with the help of a bottle. Total and dissolved hydrolysable amino acids, combined carbohydrates and dissolved organic carbon were analyzed to describe surfactant dynamics (based on phase-sensitive AC voltammetry). Flow cytometry provided additional information on bacteria and phytoplankton community composition. This data set resolves dynamics on short temporal (diurnal sampling ) and local scales (within an area of 50km^2)