scholarly journals A numerical framework for simulating episodic emissions of high-temperature marine INPs

2021 ◽  
Author(s):  
Isabelle Steinke ◽  
Paul J. DeMott ◽  
Grant Deane ◽  
Thomas C. J. Hill ◽  
Mathew Maltrud ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Temperature ◽  
Atmospheric Boundary Layer ◽  
Heterotrophic Bacteria ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Partial Explanation ◽  
Sea Surface Microlayer ◽  
Sea Spray Aerosol ◽  
Field Campaigns

Abstract. We present a framework for estimating concentrations of episodically elevated high-temperature marine ice nucleating particles (INPs) in the sea surface microlayer and their subsequent emission into the atmospheric boundary layer. These episodic INPs have been observed in multiple ship-based and coastal field campaigns, but the processes controlling their ocean concentrations and transfer to the atmosphere are not yet fully understood. We use a combination of empirical constraints and simulation outputs from an Earth System Model to explore different hypotheses for explaining the variability of INP concentrations, and the occurrence of episodic INPs, in the marine atmosphere. In our calculations, we examine two proposed oceanic sources of high-temperature INPs: heterotrophic bacteria and marine biopolymer aggregates (MBPAs). Furthermore, we assume that the emission of these INPs is determined by the production of supermicron sea spray aerosol formed from jet drops, with an entrainment probability that is described by Poisson statistics. The concentration of jet drops is derived from the number concentration of supermicron sea spray aerosol calculated from model runs. We then derive the resulting number concentrations of marine high-temperature INPs (≥ 253 K) in the atmospheric boundary layer and compare their variability to atmospheric observations of INP variability. Specifically, we compare against concentrations of episodically occurring high-temperature INPs observed during field campaigns in the Southern Ocean, the Equatorial Pacific, and the North Atlantic. We find that heterotrophic bacteria and MBPAs acting as INPs provide only a partial explanation for the observed high INP concentrations. We note, however, that there are still substantial knowledge gaps, particularly concerning the identity of the oceanic INPs contributing most frequently to episodic high-temperature INPs, their specific ice nucleation activity, and the enrichment of their concentrations during the sea-air transfer process. Therefore, targeted measurements investigating the composition of these marine INPs as well as drivers for their emission are needed, ideally in combination with modeling studies focused on the potential cloud impacts of these high-temperature INPs.

scholarly journals The Impact of Divalent Cations on the Enrichment of Soluble Saccharides in Primary Sea Spray Aerosol

Atmosphere ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 476 ◽  
Author(s):  
Steven Schill ◽  
Susannah Burrows ◽  
Elias Hasenecz ◽  
Elizabeth Stone ◽  
Timothy Bertram
Keyword(s):  
Divalent Cation ◽  
Organic Material ◽  
Large Fraction ◽  
Co Adsorption ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Volume Fractions ◽  
Sea Surface Microlayer ◽  
Sea Spray Aerosol ◽  
The Impact

Field measurements have shown that sub-micrometer sea spray aerosol (SSA) is significantly enriched in organic material, of which a large fraction has been attributed to soluble saccharides. Existing mechanistic models of SSA production struggle to replicate the observed enhancement of soluble organic material. Here, we assess the role for divalent cation mediated co-adsorption of charged surfactants and saccharides in the enrichment of soluble organic material in SSA. Using measurements of particle supersaturated hygroscopicity, we calculate organic volume fractions for molecular mimics of SSA generated from a Marine Aerosol Reference Tank. Large enhancements in SSA organic volume fractions (Xorg > 0.2) were observed for 50 nm dry diameter (dp) particles in experiments where cooperative ionic interactions were favorable (e.g., palmitic acid, Mg2+, and glucuronic acid) at seawater total organic carbon concentrations (<1.15 mM C) and ocean pH. Significantly smaller SSA organic volume fractions (Xorg < 1.5 × 10−3) were derived from direct measurements of soluble saccharide concentrations in collected SSA with dry diameters <250 nm, suggesting that organic enrichment is strongly size dependent. The results presented here indicate that divalent cation mediated co-adsorption of soluble organics to insoluble surfactants at the ocean surface may contribute to the enrichment of soluble saccharides in SSA. The extent to which this mechanism explains the observed enhancement of saccharides in nascent SSA depends strongly on the concentration, speciation, and charge of surfactants and saccharides in the sea surface microlayer.

scholarly journals Heterogeneous ice nucleation ability of aerosol particles generated from Arctic sea surface microlayer and surface seawater samples at cirrus temperatures

2021 ◽  
Vol 21 (18) ◽  
pp. 13903-13930
Author(s):  
Robert Wagner ◽  
Luisa Ickes ◽  
Allan K. Bertram ◽  
Nora Els ◽  
Elena Gorokhova ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Ice Nucleation ◽  
Sea Surface ◽  
Ice Formation ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Sea Surface Microlayer ◽  
Sea Spray Aerosol ◽  
Seawater Samples ◽  
Heterogeneous Ice Nucleation

Abstract. Sea spray aerosol particles are a recognised type of ice-nucleating particles under mixed-phase cloud conditions. Entities that are responsible for the heterogeneous ice nucleation ability include intact or fragmented cells of marine microorganisms as well as organic matter released by cell exudation. Only a small fraction of sea spray aerosol is transported to the upper troposphere, but there are indications from mass-spectrometric analyses of the residuals of sublimated cirrus particles that sea salt could also contribute to heterogeneous ice nucleation under cirrus conditions. Experimental studies on the heterogeneous ice nucleation ability of sea spray aerosol particles and their proxies at temperatures below 235 K are still scarce. In our article, we summarise previous measurements and present a new set of ice nucleation experiments at cirrus temperatures with particles generated from sea surface microlayer and surface seawater samples collected in three different regions of the Arctic and from a laboratory-grown diatom culture (Skeletonema marinoi). The particles were suspended in the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud chamber and ice formation was induced by expansion cooling. We confirmed that under cirrus conditions, apart from the ice-nucleating entities mentioned above, also crystalline inorganic salt constituents can contribute to heterogeneous ice formation. This takes place at temperatures below 220 K, where we observed in all experiments a strong immersion freezing mode due to the only partially deliquesced inorganic salts. The inferred ice nucleation active surface site densities for this nucleation mode reached a maximum of about 5×1010 m−2 at an ice saturation ratio of 1.3. Much smaller densities in the range of 108–109 m−2 were observed at temperatures between 220 and 235 K, where the inorganic salts fully deliquesced and only the organic matter and/or algal cells and cell debris could contribute to heterogeneous ice formation. These values are 2 orders of magnitude smaller than those previously reported for particles generated from microlayer suspensions collected in temperate and subtropical zones. While this difference might simply underline the strong variability of the number of ice-nucleating entities in the sea surface microlayer across different geographical regions, we also discuss how instrumental parameters like the aerosolisation method and the ice nucleation measurement technique might affect the comparability of the results amongst different studies.

scholarly journals The role of jet and film drops in controlling the mixing state of submicron sea spray aerosol particles

2017 ◽  
Vol 114 (27) ◽  
pp. 6978-6983 ◽  
Author(s):  
Xiaofei Wang ◽  
Grant B. Deane ◽  
Kathryn A. Moore ◽  
Olivia S. Ryder ◽  
M. Dale Stokes ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Volume Fraction ◽  
Water Soluble ◽  
Sea Surface ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Mixing State ◽  
Organic Species ◽  
Sea Surface Microlayer ◽  
Sea Spray Aerosol

The oceans represent a significant global source of atmospheric aerosols. Sea spray aerosol (SSA) particles comprise sea salts and organic species in varying proportions. In addition to size, the overall composition of SSA particles determines how effectively they can form cloud droplets and ice crystals. Thus, understanding the factors controlling SSA composition is critical to predicting aerosol impacts on clouds and climate. It is often assumed that submicrometer SSAs are mainly formed by film drops produced from bursting bubble-cap films, which become enriched with hydrophobic organic species contained within the sea surface microlayer. In contrast, jet drops formed from the base of bursting bubbles are postulated to mainly produce larger supermicrometer particles from bulk seawater, which comprises largely salts and water-soluble organic species. However, here we demonstrate that jet drops produce up to 43% of total submicrometer SSA number concentrations, and that the fraction of SSA produced by jet drops can be modulated by marine biological activity. We show that the chemical composition, organic volume fraction, and ice nucleating ability of submicrometer particles from jet drops differ from those formed from film drops. Thus, the chemical composition of a substantial fraction of submicrometer particles will not be controlled by the composition of the sea surface microlayer, a major assumption in previous studies. This finding has significant ramifications for understanding the factors controlling the mixing state of submicrometer SSA particles and must be taken into consideration when predicting SSA impacts on clouds and climate.

Calcium bridging drives polysaccharide co-adsorption to a proxy sea surface microlayer

2021 ◽  
Author(s):  
Kimberly Anne Carter-Fenk ◽  
Abigal Dommer ◽  
Michelle E. Fiamingo ◽  
Jeongin Kim ◽  
Rommie Amaro ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Mass Fraction ◽  
Co Adsorption ◽  
Ocean Surface ◽  
Sea Surface ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Sea Surface Microlayer ◽  
Sea Spray Aerosol ◽  
Significant Mass

Saccharides comprise a significant mass fraction of organic carbon in sea spray aerosol (SSA), but the mechanisms through which saccharides are transferred from seawater to the ocean surface and eventually...

scholarly journals Heterogeneous ice nucleation ability of aerosol particles generated from Arctic sea surface microlayer and surface seawater samples at cirrus temperatures

2021 ◽  
Author(s):  
Robert Wagner ◽  
Luisa Ickes ◽  
Allan K. Bertram ◽  
Nora Els ◽  
Elena Gorokhova ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Ice Nucleation ◽  
Sea Surface ◽  
Ice Formation ◽  
Sea Spray ◽  
Surface Microlayer ◽  
Sea Surface Microlayer ◽  
Sea Spray Aerosol ◽  
Seawater Samples ◽  
Heterogeneous Ice Nucleation

Abstract. Sea spray aerosol particles are a recognised type of ice-nucleating particles under mixed-phase cloud conditions. Entities that are responsible for the heterogeneous ice nucleation ability include intact or fragmented cells of marine microorganisms as well as organic matter released by cell exudation. Only a small fraction of sea salt aerosol is transported to the upper troposphere, but there are indications from mass-spectrometric analyses of the residuals of sublimated cirrus particles that sea salt could also contribute to heterogeneous ice nucleation under cirrus conditions. Experimental studies on the heterogeneous ice nucleation ability of sea spray aerosol particles and their proxies at temperatures below 235 K are still scarce. In our article, we summarise previous measurements and present a new set of ice nucleation experiments at cirrus temperatures with particles generated from sea surface microlayer and surface seawater samples collected in three different regions of the Arctic and from a laboratory-grown diatom culture (Skeletonema marinoi). The particles were suspended in a large cloud chamber and ice formation was induced by expansion cooling. We confirmed that under cirrus conditions, apart from the ice-nucleating entities mentioned above, also crystalline inorganic salt constituents can contribute to heterogeneous ice formation. This takes place at temperatures below 220 K, where we observed in all experiments a strong immersion freezing mode due to the only partially deliquesced inorganic salts. The inferred ice nucleation active surface site densities for this nucleation mode reached a maximum of about 5·1010 m−2 at an ice saturation ratio of 1.3. Much smaller densities in the range of 108–109 m−2 were observed at temperatures between 220 and 235 K, where the inorganic salts fully deliquesced and only the organic matter and/or algal cells and cell debris could contribute to heterogeneous ice formation. These values are two orders of magnitude smaller than those previously reported for particles generated from microlayer suspensions collected in temperate and subtropical zones. While this difference might simply underline the strong variability of the amount of ice-nucleating entities in the sea surface microlayer across different geographical regions, we also discuss how far instrumental parameters like the aerosolisation method and the ice-nucleation measurement technique might affect the comparability of the results amongst different studies.

scholarly journals Sea State and Boundary Layer Stability Limit Sea Spray Aerosol Lifetime over the Southern Ocean

2020 ◽  
Author(s):  
Sebastian Landwehr ◽  
Michele Volpi ◽  
Marzieh H Derkani ◽  
Filippo Nelli ◽  
Alberto Alberello ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Southern Ocean ◽  
Stability Limit ◽  
Sea Spray ◽  
Boundary Layer Stability ◽  
Sea State ◽  
Sea Spray Aerosol

scholarly journals Ice nucleating particles in the marine boundary layer in the Canadian Arctic during summer 2014

2019 ◽  
Vol 19 (2) ◽  
pp. 1027-1039 ◽  
Author(s):  
Victoria E. Irish ◽  
Sarah J. Hanna ◽  
Megan D. Willis ◽  
Swarup China ◽  
Jennie L. Thomas ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Surface Area ◽  
Marine Boundary Layer ◽  
Mineral Dust ◽  
Canadian Arctic ◽  
Particle Dispersion ◽  
Sea Spray ◽  
Dispersion Modelling ◽  
Air Mass ◽  
Sea Spray Aerosol

Abstract. Ice nucleating particles (INPs) in the Arctic can influence climate and precipitation in the region; yet our understanding of the concentrations and sources of INPs in this region remain uncertain. In the following, we (1) measured concentrations of INPs in the immersion mode in the Canadian Arctic marine boundary layer during summer 2014 on board the CCGS Amundsen, (2) determined ratios of surface areas of mineral dust aerosol to sea spray aerosol, and (3) investigated the source region of the INPs using particle dispersion modelling. Average concentrations of INPs at −15, −20, and −25 ∘C were 0.005, 0.044, and 0.154 L−1, respectively. These concentrations fall within the range of INP concentrations measured in other marine environments. For the samples investigated the ratio of mineral dust surface area to sea spray surface area ranged from 0.03 to 0.09. Based on these ratios and the ice active surface site densities of mineral dust and sea spray aerosol determined in previous laboratory studies, our results suggest that mineral dust is a more important contributor to the INP population than sea spray aerosol for the samples analysed. Based on particle dispersion modelling, the highest concentrations of INPs were often associated with lower-latitude source regions such as the Hudson Bay area, eastern Greenland, or north-western continental Canada. On the other hand, the lowest concentrations were often associated with regions further north of the sampling sites and over Baffin Bay. A weak correlation was observed between INP concentrations and the time the air mass spent over bare land, and a weak negative correlation was observed between INP concentrations and the time the air mass spent over ice and open water. These combined results suggest that mineral dust from local sources is an important contributor to the INP population in the Canadian Arctic marine boundary layer during summer 2014.

scholarly journals Study of the overturning length scales at the Spanish planetary boundary layer

2015 ◽  
Vol 2 (6) ◽  
pp. 1531-1551
Author(s):  
P. López ◽  
J. L. Cano
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Power Law ◽  
Power Laws ◽  
Data Sets ◽  
The Novel ◽  
Convective Conditions ◽  
Mixing Conditions ◽  
Thorpe Scale ◽  
Field Campaigns

Abstract. The focus of this paper is to analyze the behaviour of the maximum Thorpe displacement (dT)max and the Thorpe scale LT at the atmospheric boundary layer (ABL), extending previous research with new data and improving our studies related to the novel use of the Thorpe method applied to ABL. The maximum Thorpe displacements varies between −900 and 950 m for the different field campaigns. The Thorpe scale LT ranges between 0.2 and 680 m for the different data sets which cover different stratified mixing conditions (turbulence sher-driven and convective regions). We analyze the relation between dT)max and the Thorpe scale LT and we deduce that they verify a power law. We also deduce that there is a difference in exponents of the power laws for convective conditions and shear-driven conditions. This different power laws could identify overturns created under different mechanisms.

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