scholarly journals Atmospheric Ageing of Inorganic Sea Spray Aerosol: Implications for Hygroscopicity and Cloud Activation Potential

2020 ◽  
Author(s):  
Bernadette Rosati ◽  
Sigurd Christiansen ◽  
Anders Dinesen ◽  
Pontus Roldin ◽  
Andreas Massling ◽  
...  
Keyword(s):  
Uv Light ◽  
Sea Salt ◽  
Sea Spray ◽  
Hygroscopic Growth ◽  
Sea Salt Aerosol ◽  
Activation Potential ◽  
Sea Spray Aerosol ◽  
Marine Areas ◽  
Cloud Activation ◽  
Additional Explanation

Abstract Sea spray aerosol (SSA) contributes significantly to natural aerosol particle concentrations globally, in marine areas even dominantly. The potential changes of the omnipresent inorganic fraction of SSA due to atmospheric ageing is largely unexplored. We demonstrate that ageing of liquid NaCl and artificial sea salt aerosol by exposure to ozone and UV light leads to a substantial decrease in hygroscopicity and cloud activation potential. The results point towards surface reactions that are more crucial for small particles and the formation of salt structures with water bound within the aerosols, termed hydrates. Our findings suggest an increased formation of hydrate forming salts during ageing and the presence of hydrates in dried SSA. Field observations indicate a reduced hygroscopic growth of sub-micrometre SSA in the marine atmosphere compared to pure NaCl which is typically attributed to organic matter or sulphates. Aged inorganic sea salt offers an additional explanation for reduced hygroscopicity and cloud activation potential.

scholarly journals The impact of atmospheric oxidation on hygroscopicity and cloud droplet activation of inorganic sea spray aerosol

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bernadette Rosati ◽  
Sigurd Christiansen ◽  
Anders Dinesen ◽  
Pontus Roldin ◽  
Andreas Massling ◽  
...  
Keyword(s):  
Growth Factor ◽  
Uv Light ◽  
Cloud Droplet ◽  
Sea Salt ◽  
Sea Spray ◽  
Hygroscopic Growth ◽  
Activation Potential ◽  
Sea Spray Aerosol ◽  
Cloud Activation ◽  
The Impact

AbstractSea spray aerosol (SSA) contributes significantly to natural aerosol particle concentrations globally, in marine areas even dominantly. The potential changes of the omnipresent inorganic fraction of SSA due to atmospheric ageing is largely unexplored. In the atmosphere, SSA may exist as aqueous phase solution droplets or as dried solid or amorphous particles. We demonstrate that ageing of liquid NaCl and artificial sea salt aerosol by exposure to ozone and UV light leads to a substantial decrease in hygroscopicity and cloud activation potential of the dried particles of the same size. The results point towards surface reactions on the liquid aerosols that are more crucial for small particles and the formation of salt structures with water bound within the dried aerosols, termed hydrates. Our findings suggest an increased formation of hydrate forming salts during ageing and the presence of hydrates in dried SSA. Field observations indicate a reduced hygroscopic growth factor of sub-micrometre SSA in the marine atmosphere compared to fresh laboratory generated NaCl or sea salt of the same dry size, which is typically attributed to organic matter or sulphates. Aged inorganic sea salt offers an additional explanation for such a measured reduced hygroscopic growth factor and cloud activation potential.

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

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.

scholarly journals Predicted hygroscopic growth of sea salt aerosol

2001 ◽  
Vol 106 (D22) ◽  
pp. 28259-28274 ◽  
Author(s):  
Yi Ming ◽  
Lynn M. Russell
Keyword(s):  
Sea Salt ◽  
Hygroscopic Growth ◽  
Sea Salt Aerosol

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

2012 ◽  
Vol 12 (1) ◽  
pp. 89-101 ◽  
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.

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

2016 ◽  
Vol 16 (14) ◽  
pp. 9003-9018 ◽  
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.

Global scale emission and distribution of sea-spray aerosol: Sea-salt and organic enrichment

2010 ◽  
Vol 44 (5) ◽  
pp. 670-677 ◽  
Author(s):  
E. Vignati ◽  
M.C. Facchini ◽  
M. Rinaldi ◽  
C. Scannell ◽  
D. Ceburnis ◽  
...  
Keyword(s):  
Global Scale ◽  
Sea Salt ◽  
Organic Enrichment ◽  
Sea Spray ◽  
Sea Spray Aerosol

scholarly journals The organic fraction of bubble-generated, accumulation mode Sea Spray Aerosol (SSA)

2010 ◽  
Vol 10 (6) ◽  
pp. 2867-2877 ◽  
Author(s):  
R. L. Modini ◽  
B. Harris ◽  
Z. D. Ristovski
Keyword(s):  
Volume Fraction ◽  
Biologically Active ◽  
Global Ocean ◽  
Sea Spray ◽  
Natural Seawater ◽  
Hygroscopic Growth ◽  
Organic Fraction ◽  
Accumulation Mode ◽  
Order Of Magnitude ◽  
Sea Spray Aerosol

Abstract. Recent studies have detected a dominant accumulation mode (~100 nm) in the Sea Spray Aerosol (SSA) number distribution. There is evidence to suggest that particles in this mode are composed primarily of organics. To investigate this hypothesis we conducted experiments on NaCl, artificial SSA and natural SSA particles with a Volatility-Hygroscopicity-Tandem-Differential-Mobility-Analyser (VH-TDMA). NaCl particles were atomiser generated and a bubble generator was constructed to produce artificial and natural SSA particles. Natural seawater samples for use in the bubble generator were collected from biologically active, terrestrially-affected coastal water in Moreton Bay, Australia. Differences in the VH-TDMA-measured volatility curves of artificial and natural SSA particles were used to investigate and quantify the organic fraction of natural SSA particles. Hygroscopic Growth Factor (HGF) data, also obtained by the VH-TDMA, were used to confirm the conclusions drawn from the volatility data. Both datasets indicated that the organic fraction of our natural SSA particles evaporated in the VH-TDMA over the temperature range 170–200 °C. The organic volume fraction for 71–77 nm natural SSA particles was 8±6%. Organic volume fraction did not vary significantly with varying water residence time (40 s to 24 h) in the bubble generator or SSA particle diameter in the range 38–173 nm. At room temperature we measured shape- and Kelvin-corrected HGF at 90% RH of 2.46±0.02 for NaCl, 2.35±0.02 for artifical SSA and 2.26±0.02 for natural SSA particles. Overall, these results suggest that the natural accumulation mode SSA particles produced in these experiments contained only a minor organic fraction, which had little effect on hygroscopic growth. Our measurement of 8±6% is an order of magnitude below two previous measurements of the organic fraction in SSA particles of comparable sizes. We stress that our results were obtained using coastal seawater and they can't necessarily be applied on a regional or global ocean scale. Nevertheless, considering the order of magnitude discrepancy between this and previous studies, further research with independent measurement techniques and a variety of different seawaters is required to better quantify how much organic material is present in accumulation mode SSA.

scholarly journals Modelling of sea salt pollution over Europe: key uncertainties and comparison with observations

2011 ◽  
Vol 11 (4) ◽  
pp. 11143-11204
Author(s):  
S. Tsyro ◽  
W. Aas ◽  
J. Soares ◽  
M. Sofiev ◽  
H. Berge ◽  
...  
Keyword(s):  
Air Quality ◽  
Source Function ◽  
Temporal Correlation ◽  
Sea Salt ◽  
Sea Spray ◽  
Model Calculations ◽  
Sea Salt Aerosol ◽  
Calculation Results ◽  
Meteorological Input ◽  
Removal Processes

Abstract. Sea spray can significantly affect the air quality. Sea salt can cause enhanced concentrations of particulate matter and change particle chemical composition, in particular in coastal areas, and therefore should be accounted for in air quality modelling. We have used an EMEP Unified model to calculate sea salt concentrations and depositions over Europe, focusing on studying the effects of uncertainties in sea salt production and lifetime on calculation results. Model calculations of sea salt have been compared with EMEP observations of sodium concentrations in air and precipitation for a four year period, from 2004 to 2007, including size (fine/coarse) resolved EMEP intensive measurements in 2006 and 2007. In the presented calculations, sodium air concentrations are between 8 and 46% overestimated, whereas concentrations in precipitation are systematically underestimated by 65–70% for years 2004–2007. Unfortunately, thus far performed tests have failed to give a clear answer regarding the reason for this underestimation and further studies are needed. The model is found to reproduce fairly well the spatial distribution of Na+ in air and precipitation over Europe, and to capture most of sea salt episodes. The paper presents the main findings from a series of tests in which we compare several different sea spray source functions and also look at the effects of meteorological input and the efficiency of removal processes on calculated sea salt concentrations. Finally, sea salt calculations with the EMEP model have been compared with results from the SILAM model and observations for 2007. While the models produce fairly close results for Na+ at most of 26 measurement sites, discrepancies in terms of bias and temporal correlation are also found. Those differences are probably due to differences in the representation of source function and treatment of sea salt aerosol, and also due to different meteorology used for model runs and due to a finer grid resolution of the SILAM model compared to EMEP. This study contributes to getting a better insight on uncertainties associated with sea salt calculations with the EMEP model and towards further improvement of EMEP aerosol modelling.

scholarly journals Sub-Antarctic marine aerosol: dominant contributions from biogenic sources

2013 ◽  
Vol 13 (17) ◽  
pp. 8669-8694 ◽  
Author(s):  
J. Schmale ◽  
J. Schneider ◽  
E. Nemitz ◽  
Y. S. Tang ◽  
U. Dragosits ◽  
...  
Keyword(s):  
Methanesulfonic Acid ◽  
Sea Salt ◽  
Submicron Particles ◽  
Sea Spray ◽  
Local Fauna ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Organic Factor ◽  
Sea Spray Aerosol ◽  
Highly Correlated

Abstract. Biogenic influences on the composition and characteristics of aerosol were investigated on Bird Island (54°00' S, 38°03' W) in the South Atlantic during November and December 2010. This remote marine environment is characterised by large seabird and seal colonies. The chemical composition of the submicron particles, measured by an aerosol mass spectrometer (AMS), was 21% non-sea-salt sulfate, 2% nitrate, 8% ammonium, 22% organics and 47% sea salt including sea salt sulfate. A new method to isolate the sea spray signature from the high-resolution AMS data was applied. Generally, the aerosol was found to be less acidic than in other marine environments due to the high availability of ammonia, from local fauna emissions. By positive matrix factorisation five different organic aerosol (OA) profiles could be isolated: an amino acid/amine factor (AA-OA, 18% of OA mass), a methanesulfonic acid OA factor (MSA-OA, 25%), a marine oxygenated OA factor (M-OOA, 41%), a sea spray OA fraction (SS-OA, 7%) and locally produced hydrocarbon-like OA (HOA, 9%). The AA-OA was dominant during the first two weeks of November and found to be related with the hatching of penguins in a nearby colony. This factor, rich in nitrogen (N : C ratio = 0.13), has implications for the biogeochemical cycling of nitrogen in the area as particulate matter is often transported over longer distances than gaseous N-rich compounds. The MSA-OA was mainly transported from more southerly latitudes where phytoplankton bloomed. The bloom was identified as one of three sources for particulate sulfate on Bird Island, next to sea salt sulfate and sulfate transported from South America. M-OOA was the dominant organic factor and found to be similar to marine OA observed at Mace Head, Ireland. An additional OA factor highly correlated with sea spray aerosol was identified (SS-OA). However, based on the available data the type of mixture, internal or external, could not be determined. Potassium was not associated with sea salt particles during 19% of the time, indicating the presence of biogenic particles in addition to the MSA-OA and AA-OA factors.

scholarly journals Primary marine aerosol emissions: size resolved eddy covariance measurements with estimates of the sea salt and organic carbon fractions

2007 ◽  
Vol 7 (5) ◽  
pp. 13345-13400 ◽  
Author(s):  
E. D. Nilsson ◽  
E. M. Mårtensson ◽  
J. S. Van Ekeren ◽  
G. de Leeuw ◽  
M. Moerman ◽  
...  
Keyword(s):  
Wind Speed ◽  
Organic Carbon ◽  
Eddy Covariance ◽  
Sea Salt ◽  
Sea Spray ◽  
Marine Aerosol ◽  
Particle Counter ◽  
Wind Speeds ◽  
Sea Salt Aerosol ◽  
Aerosol Emissions

Abstract. Primary marine aerosol fluxes were measured using eddy covariance (EC), a condensation particle counter (CPC) and an optical particle counter (OPC) with a heated inlet. The later was used to discriminate between sea salt and total aerosol. Measurements were made from the 25 m tower at the research station Mace Head at the Irish west coast, May to September 2002. The aerosol fluxes were dominated by upward fluxes, sea spray from bubble bursting at the ocean surface. The sea salt aerosol number emissions increased two orders of magnitude with declining diameter from 1 to 0.1 μm where it peaked at values of 105 to 107 particles m−2s−1. The sea salt emissions increased at all sizes in the wind range 4 to 22 ms−1, in consistency with a power function of the wind speed. The sea salt emission data were compared to three recent sub micrometer sea salt source parameterisations. The best agreement was with Mårtensson et al. (2003), which appear to apply from 0.1 to 1.1 μm diameters in temperate water (12°C) as well as tropical water (25°C). The total aerosol emissions were independent of the wind speed below 10 ms−1, but increased with the wind above 10 ms−1. The aerosol volume emissions were larger for the total aerosol than for the sea salt at all wind speeds, while the sea salt number emissions approached the total number emissions at 15 ms−1. It is speculated that this is caused by organic carbon in the surface water that is depleted at high wind speeds. The data are consistent with an internal aerosol mixture of sea salt, organic carbon and water. Using the aerosol model by Ellison et al. (1999) (a mono-layer of organic carbon surrounding a water-sea-salt brine) we show that the total and sea salt aerosol emissions are consistent. This predict that the organic carbon fraction increase with decreasing diameter from a few % at 1 μm over 50% at about 0.5 μm to about 90% at 0.1 μm, in consistency with simultaneous chemical data by Cavalli et al. (2004). The combined models of Mårtensson et al. (2003) and Ellison et al. (1999) reproduce the observed total aerosol emissions and offer an approach to model the organic sea spray fraction.

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