Organic Enrichment, Physical Phase State, and Surface Tension Depression of Nascent Core–Shell Sea Spray Aerosols during Two Phytoplankton Blooms

Abstract. The aerosol driven radiative effects on marine low-level cloud represent a large uncertainty in climate simulations, in particular over the Southern Ocean, which is also an important region for sea spray aerosol production. Observations of sea spray aerosol organic enrichment and the resulting impact on water uptake over the remote southern hemisphere are scarce, and are therefore the region is under-represented in existing parameterisations. The Surface Ocean Aerosol Production (SOAP) voyage was a 23 day voyage which sampled three phytoplankton blooms in the highly productive water of the Chatham Rise, east of New Zealand. In this study we examined the enrichment of organics to nascent sea spray aerosol and the modifications to sea spray aerosol water uptake using in-situ chamber measurements of seawater samples taken during the SOAP voyage. Primary marine organics contributed up to 23 % of the sea spray mass for particles with diameter less than approximately 1 μm, and up to 87 % of the particle volume in the Aitken mode. The composition of the organic fraction was consistent throughout the voyage and was largely comprised of a polysaccharide-like component, characterised by very low alkane to hydroxyl concentration ratios of approximately 0.1–0.2. The enrichment of organics was compared to the output from the chlorophyll-a based sea spray aerosol parameterisation suggested by Gantt et al. (2011) and the OCEANFILMS models. OCEANFILMS improved on the representation of the organic fraction predicted using chlorophyll-a, in particular when the co-adsoprtion of polysaccharides was included, however the model still under predicted the proportion of polysaccharides by an average of 33 %. Nascent sea spray aerosol hygroscopic growth factors averaged 1.93 ± 0.08, and did not decrease with increasing sea spray aerosol organic fractions. The observed hygroscopicity was greater than expected from the assumption of full solubility, particularly during the most productive phytoplankton bloom (B1), during which organic fractions were greater than approximately 0.4. The water uptake behaviour observed in this study is consistent with that observed for other measurements of phytoplankton blooms, and was attributed to the surface partitioning of the organic components which leads to a decrease in particle surface tension and an increase in hygroscopicity. The compressed film model was used to estimate the influence of surface partitioning and the error in the modelled hygroscopicity was low only when the entire organic fraction was available to partition to the particle surface. The modelled sea spray aerosol hygroscopicity at high organic fractions was underestimated when only a portion of the organic component was available to be partitioned to the surface. The findings from the SOAP voyage highlight the influence of biologically-sourced organics on sea spray aerosol composition, these data improve the capacity to parameterise sea spray aerosol organic enrichment and water uptake.

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Sea spray aerosol organic enrichment, water uptake and surface tension effects

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-7955-2020 ◽

2020 ◽

Vol 20 (13) ◽

pp. 7955-7977 ◽

Cited By ~ 2

Author(s):

Luke T. Cravigan ◽

Marc D. Mallet ◽

Petri Vaattovaara ◽

Mike J. Harvey ◽

Cliff S. Law ◽

...

Keyword(s):

Surface Tension ◽

Chlorophyll A ◽

Water Uptake ◽

Organic Enrichment ◽

Sea Spray ◽

Organic Fraction ◽

Phytoplankton Blooms ◽

Aerosol Composition ◽

Sea Spray Aerosol ◽

Organic Fractions

Abstract. The aerosol-driven radiative effects on marine low-level cloud represent a large uncertainty in climate simulations, in particular over the Southern Ocean, which is also an important region for sea spray aerosol production. Observations of sea spray aerosol organic enrichment and the resulting impact on water uptake over the remote Southern Hemisphere are scarce, and therefore the region is under-represented in existing parameterisations. The Surface Ocean Aerosol Production (SOAP) voyage was a 23 d voyage which sampled three phytoplankton blooms in the highly productive water of the Chatham Rise, east of New Zealand. In this study we examined the enrichment of organics to nascent sea spray aerosol and the modifications to sea spray aerosol water uptake using in situ chamber measurements of seawater samples taken during the SOAP voyage. Primary marine organics contributed up to 23 % of the sea spray mass for particles with diameter less than approximately 1 µm and up to 79 % of the particle volume for 50 nm diameter sea spray. The composition of the submicron organic fraction was consistent throughout the voyage and was largely composed of a polysaccharide-like component, characterised by very low alkane-to-hydroxyl-concentration ratios of approximately 0.1–0.2. The enrichment of organics was compared to the output from the chlorophyll-a-based sea spray aerosol parameterisation suggested by Gantt et al. (2011) and the OCEANFILMS (Organic Compounds from Ecosystems to Aerosols: Natural Films and Interfaces via Langmuir Molecular Surfactants) models. OCEANFILMS improved on the representation of the organic fraction predicted using chlorophyll a, in particular when the co-adsorption of polysaccharides was included; however, the model still under-predicted the proportion of polysaccharides by an average of 33 %. Nascent 50 nm diameter sea spray aerosol hygroscopic growth factors measured at 90 % relative humidity averaged 1.93±0.08 and did not decrease with increasing sea spray aerosol organic fractions. The observed hygroscopicity was greater than expected from the assumption of full solubility, particularly during the most productive phytoplankton bloom (B1), during which organic fractions were greater than approximately 0.4. The water uptake behaviour observed in this study is consistent with that observed for other measurements of phytoplankton blooms and can be partially attributed to the presence of sea salt hydrates, which lowers the sea spray aerosol hygroscopicity when the organic enrichment is low. The inclusion of surface tension effects only marginally improved the modelled hygroscopicity, and a significant discrepancy between the observed and modelled hygroscopicity at high organic volume fractions remained. The findings from the SOAP voyage highlight the influence of biologically sourced organics on sea spray aerosol composition; these data improve the capacity to parameterise sea spray aerosol organic enrichment and water uptake.

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review of Sea spray aerosol organic enrichment, water uptake and surface tension effects

10.5194/acp-2019-797-rc2 ◽

2019 ◽

Author(s):

Christopher Oxford

Keyword(s):

Surface Tension ◽

Water Uptake ◽

Organic Enrichment ◽

Sea Spray ◽

Sea Spray Aerosol

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Supplementary material to "Sea spray aerosol organic enrichment, water uptake and surface tension effects"

10.5194/acp-2019-797-supplement ◽

2019 ◽

Author(s):

Luke T. Cravigan ◽

Marc D. Mallet ◽

Petri Vaattovaara ◽

Mike J. Harvey ◽

Cliff S. Law ◽

...

Keyword(s):

Surface Tension ◽

Water Uptake ◽

Organic Enrichment ◽

Sea Spray ◽

Sea Spray Aerosol ◽

Supplementary Material

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Linking variations in sea spray aerosol particle hygroscopicity to composition during two microcosm experiments

10.5194/acp-2016-36 ◽

2016 ◽

Author(s):

Sara D. Forestieri ◽

Gavin C. Cornwell ◽

Taylor M. Helgestad ◽

Kathryn A. Moore ◽

Christopher Lee ◽

...

Keyword(s):

Light Scattering ◽

Relative Humidity ◽

Salt Content ◽

Sea Salt ◽

Sea Spray ◽

Hygroscopic Growth ◽

Phytoplankton Blooms ◽

Aerosol Composition ◽

Sea Spray Aerosol ◽

Indoor And Outdoor

Abstract. The extent to which water uptake influences the light scattering ability of marine sea spray aerosol (SSA) particles depends critically on SSA chemical composition. The organic fraction of SSA can increase during phytoplankton blooms, decreasing the salt content and therefore the hygroscopicity of the particles. In this study, subsaturated hygroscopic growth factors at 85 % relative humidity (GF(85 %)) of SSA particles were quantified during two induced phytoplankton blooms in marine aerosol reference tanks (MARTs). One MART was illuminated with fluorescent lights and the other was illuminated with sunlight, referred to as the "indoor" and "outdoor" MARTs, respectively. GF(85 %) values for SSA particles were derived from measurements of light scattering and particle size distributions, concurrently with online single particle and bulk aerosol composition measurements. During both microcosm experiments, the observed bulk average GF(85 %) values were depressed substantially relative to pure, inorganic sea salt, by 10 to 19 %, with a one (indoor MART) and six (outdoor MART) day lag between GF(85 %) depression and the peak chlorophyll-a concentrations. The fraction of organiccontaining SSA particles generally increased after the peak of the phytoplankton blooms. The GF(85 %) values were inversely correlated with the fraction of particles containing organic or other biological markers. This indicates these particles were less hygroscopic than the particles identified as predominately sea salt containing and demonstrates a clear relationship between SSA particle composition and the sensitivity of light scattering to variations in relative humidity. The implications of these observations to the direct climate effects of SSA particles are discussed.

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Phytoplankton blooms weakly influence the cloud forming ability of sea spray aerosol

Geophysical Research Letters ◽

10.1002/2016gl069922 ◽

2016 ◽

Vol 43 (18) ◽

pp. 9975-9983 ◽

Cited By ~ 29

Author(s):

Douglas B. Collins ◽

Timothy H. Bertram ◽

Camille M. Sultana ◽

Christopher Lee ◽

Jessica L. Axson ◽

...

Keyword(s):

Sea Spray ◽

Phytoplankton Blooms ◽

Sea Spray Aerosol

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Effect of primary organic sea spray emissions on cloud condensation nuclei concentrations

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-89-2012 ◽

2012 ◽

Vol 12 (1) ◽

pp. 89-101 ◽

Cited By ~ 46

Author(s):

D. M. Westervelt ◽

R. H. Moore ◽

A. Nenes ◽

P. J. Adams

Keyword(s):

Surface Tension ◽

Southern Ocean ◽

Source Function ◽

Cloud Condensation Nuclei ◽

Organic Aerosol ◽

Sea Salt ◽

Sea Spray ◽

Aerosol Emission ◽

Sea Spray Aerosol ◽

Surfactant Effects

Abstract. This work estimates the primary marine organic aerosol global emission source and its impact on cloud condensation nuclei (CCN) concentrations by implementing an organic sea spray source function into a series of global aerosol simulations. The source function assumes that a fraction of the sea spray emissions, depending on the local chlorophyll concentration, is organic matter in place of sea salt. Effect on CCN concentrations (at 0.2% supersaturation) is modeled using the Two-Moment Aerosol Sectional (TOMAS) microphysics algorithm coupled to the GISS II-prime general circulation model. The presence of organics affects CCN activity in competing ways: by reducing the amount of solute available in the particle and decreasing surface tension of CCN. To model surfactant effects, surface tension depression data from seawater samples taken near the Georgia coast were applied as a function of carbon concentrations. A global marine organic aerosol emission rate of 17.7 Tg C yr−1 is estimated from the simulations. Marine organics exert a localized influence on CCN(0.2%) concentrations, decreasing regional concentrations by no more than 5% and by less than 0.5% over most of the globe, assuming direct replacement of sea salt aerosol with organic aerosol. The decrease in CCN concentrations results from the fact that the decrease in particle solute concentration outweighs the organic surfactant effects. The low sensitivity of CCN(0.2%) to the marine organic emissions is likely due to the small compositional changes: the mass fraction of OA in accumulation mode aerosol increases by only ~15% in a biologically active region of the Southern Ocean. To test the sensitivity to uncertainty in the sea spray emissions process, we relax the assumption that sea spray aerosol number and mass remain fixed and instead can add to sea spray emissions rather than replace existing sea salt. In these simulations, we find that marine organic aerosol can increase CCN by up to 50% in the Southern Ocean and 3.7% globally during the austral summer. This vast difference in CCN impact highlights the need for further observational exploration of the sea spray aerosol emission process as well as evaluation and development of model parameterizations.

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Linking variations in sea spray aerosol particle hygroscopicity to composition during two microcosm experiments

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-9003-2016 ◽

2016 ◽

Vol 16 (14) ◽

pp. 9003-9018 ◽

Cited By ~ 21

Author(s):

Sara D. Forestieri ◽

Gavin C. Cornwell ◽

Taylor M. Helgestad ◽

Kathryn A. Moore ◽

Christopher Lee ◽

...

Keyword(s):

Organic Matter ◽

Light Scattering ◽

Time Lag ◽

Sea Salt ◽

Sea Spray ◽

Phytoplankton Blooms ◽

Chl A ◽

Volume Fractions ◽

Sea Spray Aerosol ◽

Indoor And Outdoor

Abstract. The extent to which water uptake influences the light scattering ability of marine sea spray aerosol (SSA) particles depends critically on SSA chemical composition. The organic fraction of SSA can increase during phytoplankton blooms, decreasing the salt content and therefore the hygroscopicity of the particles. In this study, subsaturated hygroscopic growth factors at 85 % relative humidity (GF(85 %)) of predominately submicron SSA particles were quantified during two induced phytoplankton blooms in marine aerosol reference tanks (MARTs). One MART was illuminated with fluorescent lights and the other was illuminated with sunlight, referred to as the "indoor" and "outdoor" MARTs, respectively. Optically weighted GF(85 %) values for SSA particles were derived from measurements of light scattering and particle size distributions. The mean optically weighted SSA diameters were 530 and 570 nm for the indoor and outdoor MARTs, respectively. The GF(85 %) measurements were made concurrently with online particle composition measurements, including bulk composition (using an Aerodyne high-resolution aerosol mass spectrometer) and single particle (using an aerosol time-of-flight mass spectrometer) measurement, and a variety of water-composition measurements. During both microcosm experiments, the observed optically weighted GF(85 %) values were depressed substantially relative to pure inorganic sea salt by 5 to 15 %. There was also a time lag between GF(85 %) depression and the peak chlorophyll a (Chl a) concentrations by either 1 (indoor MART) or 3-to-6 (outdoor MART) days. The fraction of organic matter in the SSA particles generally increased after the Chl a peaked, also with a time lag, and ranged from about 0.25 to 0.5 by volume. The observed depression in the GF(85 %) values (relative to pure sea salt) is consistent with the large observed volume fractions of non-refractory organic matter (NR-OM) comprising the SSA. The GF(85 %) values exhibited a reasonable negative correlation with the SSA NR-OM volume fractions after the peak of the blooms (i.e., Chl a maxima); i.e., the GF(85 %) values generally decreased when the NR-OM volume fractions increased. The GF(85 %) vs. NR-OM volume fraction relationship was interpreted using the Zdanovskii–Stokes–Robinson (ZSR) mixing rule and used to estimate the GF(85 %) of the organic matter in the nascent SSA. The estimated pure NR-OM GF(85 %) values were 1.16 ± 0.09 and 1.23 ± 0.10 for the indoor and outdoor MARTS, respectively. These measurements demonstrate a clear relationship between SSA particle composition and the sensitivity of light scattering to variations in relative humidity. The implications of these observations to the direct climate effects of SSA particles are discussed.

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Wind speed dependent size-resolved parameterization for the organic enrichment of sea spray

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-10525-2011 ◽

2011 ◽

Vol 11 (4) ◽

pp. 10525-10555 ◽

Cited By ~ 3

Author(s):

B. Gantt ◽

N. Meskhidze ◽

M. C. Facchini ◽

M. Rinaldi ◽

D. Ceburnis ◽

...

Keyword(s):

Chemical Composition ◽

Wind Speed ◽

Organic Carbon ◽

Chlorophyll A ◽

Surface Wind ◽

Surface Wind Speed ◽

Organic Enrichment ◽

Significant Source ◽

Sea Spray ◽

Chl A

Abstract. For oceans to become a significant source of primary organic aerosol (POA), sea spray must be highly enriched with organics relative to the bulk seawater. We propose that organic enrichment at the air-sea interface, chemical composition of seawater, and the aerosol size are three main parameters controlling the organic mass fraction of sea spray aerosol (OMss). To test this hypothesis, we developed a new marine POA emission function based on a conceptual relationship between the organic enrichment at the air-sea interface and surface wind speed. The resulting parameterization is explored using aerosol chemical composition and surface wind speed from Atlantic and Pacific coastal stations, and satellite-derived ocean concentrations of chlorophyll-a, dissolved organic carbon, and particulate organic carbon. Of all the parameters examined, a multi-variable logistic regression revealed that the combination of 10 m wind speed and surface chlorophyll-a concentration ([Chl-a]) are the most consistent predictors of OMss. This relationship, combined the published aerosol size dependence of OMss, resulted in a new parameterization for the organic carbon fraction of sea spray. Global marine primary organic emission is investigated here by applying this newly-developed relationship to existing sea spray emission functions, satellite-derived [Chl-a], and modeled 10 meter winds. Analysis of model simulations show that global annual submicron marine organic emission associated with sea spray is estimated to be from 2.8 to 5.6 Tg C yr−1. This study provides additional evidence that marine primary organic aerosols are a globally significant source of organics in the atmosphere.

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Numerical simulation of water film edge dynamics

10.5194/egusphere-egu21-14110 ◽

2021 ◽

Author(s):

Anna Zotova ◽

Yuliya Troitskaya ◽

Alexander Kandaurov ◽

Daniil Sergeev

Keyword(s):

Numerical Simulation ◽

Surface Tension ◽

Three Dimensional ◽

Water Film ◽

Free Edge ◽

Sea Spray ◽

Initial Moment ◽

Interfacial Flows ◽

Strong Winds ◽

Surface Tension Forces

Fundamental contribution to the formation of sea spray under strong winds is provided by the bag-breakup phenomenon - rupture of film in the form of parachute [1]. Breaking of water film into droplets is caused, among other factors, by processes occurring on the free edge of the film moving under action of surface tension forces. The study of these processes will help to understand how characteristics of the film and the drops appearing after its rupture are related.Using the Basilisk software package with Volume of Fluid advection scheme for interfacial flows, numerical simulation of three-dimensional water film placed in domain filled with air was carried out. The water film was placed into domain filled with air. One of the edges of the film is free, and the second is fixed on the left boundary of the domain; along the third coordinate, the boundary conditions are periodic. At the initial moment of time, the film is defined by a sheet with variable thickness - the upper boundary has the form of a cosine. The change in the shape of the film over time was recorded. It is revealed that the inhomogeneity of the film thickness leads to the appearance of a significant curvature of the edge of the film as it moves under the action of surface tension forces.This work was supported by the RFBR grants (20-05-00322, 21-55-50005, 21-55-52005) and RSF grant 19-17-00209.[1] Troitskaya, Y. et al. Bag-breakup fragmentation as the dominant mechanism of sea-spray production in high winds. Sci. Rep. 7, 1614 (2017).

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