Regional impacts of ultrafine particle emissions from the surface of the Great Lakes

Chung, S. H.; Basarab, B.; VanReken, T. M.

doi:10.5194/acp-11-12601-2011

Cited by 18 publications

(42 citation statements)

References 50 publications

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“…Although a systematically varying salinity did not have a considerable effect on foam decay for oceanographically relevant salinities (say 30-40 g/kg), even low-salt concentrations drastically enhance the foaming characteristics of freshwater. This result raises concern on the use of saltwater models to predict bubble-mediated air-water interactions in freshwater bodies (see, e.g., Chung et al, 2011) .…”

Section: Discussionmentioning

confidence: 99%

A Systematic Analysis of the Salinity Effect on Air Bubbles Evolution: Laboratory Experiments in a Breaking Wave Analog

Harb

Foroutan

2019

JGR Oceans

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The evolution of air bubbles after breaking waves plays an important role in gas and particle exchange between water bodies and the atmosphere. To improve our understanding of the impacts of salinity on this process, we systematically investigate the effect of salt concentrations ranging from 0 to 40 g/kg on the volume and size distributions of subsurface bubble plumes and surface foams in a laboratory breaking wave analog. Our experimental setup utilizes an intermittent plunging sheet to simulate breaking waves, while two synchronized digital cameras were used to monitor the temporal evolution of bubble plumes and surface foams. We first highlight the importance of plunging sheet intermittency on surface foam evolution. We then show that increasing salinity enhances the entrainment of submillimeter bubbles but has a less significant effect on larger supramillimeter bubbles. We observed that the foam area in saltier waters is consistently higher than that in freshwater throughout the foam decay phase. Furthermore, our investigation of surface bubble sizes shows that salinity has a more distinct effect on smaller (sub 2 mm) than on larger bubbles. This suggests that salinity may have a more pronounced impact on jet than on film drops ejection mechanisms. Finally, we conclude that the change in salinity within the typical oceanographic range is likely not a major factor for bubble-mediated interactions at the water surface during breaking waves. However, even low-salt concentrations greatly alter air entrainment characteristics in freshwater systems. Plain Language SummaryWhen sea waves break, they entrain large volumes of air in the form of bubbles. These bubbles rise up to the surface and burst, ejecting gas and small droplets into the air. This ejection mechanism plays an important role in air quality and climate dynamics. The effect of water salinity on this process is still not well understood. We used an intermittent plunging waterfall inside a laboratory tank and digital cameras to monitor the evolution of bubbles within and at the surface of water. We found that the jet intermittency affects the foam evolution on the surface following the wave-breaking event. Increasing water salinity led to an increase in the entrained bubbles number, and potentially the air volume injected by the breaking waves. We also observed a larger and more persistent foam patch in more saline water than in freshwater. The size of the surface bubbles in the foam patch was also affected by the salinity indicating that the latter affects the bubble-bursting mechanism on the surface. We conclude that water salinity has a measurable effect on the air volume and bubble sizes injected by breaking waves and should be accounted for in future air-sea interactions studies.

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Section: Discussionmentioning

confidence: 99%

A Systematic Analysis of the Salinity Effect on Air Bubbles Evolution: Laboratory Experiments in a Breaking Wave Analog

Harb

Foroutan

2019

JGR Oceans

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“…They concluded that these particles were emitted due to wind-driven processes at the lake surface, a phenomenon that had not been previously reported. The potential impacts of this newly discovered source were later evaluated by Chung et al (2011), who found that the mechanism could enhance particle number concentrations by 20% in the remote northern Great Lakes region and 5% over other parts of the Great Lakes.…”

Section: Introductionmentioning

confidence: 99%

Influence of air mass origin on aerosol properties at a remote Michigan forest site

VanReken

Mwaniki

Wallace

et al. 2015

Atmospheric Environment

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“…SSA contributes to both direct and indirect radiative forcing on a global scale (Lohmann and Feichter, 2005;Murphy et al, 1998). Aerosol generation from freshwater sources, such as the Laurentian Great Lakes, has been far less studied, with only a single ambient measurement (Slade et al, 2010) and modeling study (Chung et al, 2011) having examined the process to our knowledge. Slade et al (2010) observed the production of ultrafine (< 40 nm) aerosol, which increased in concentration as a function of wind speed, during periods of white-capped waves over Lake Michigan.…”

Section: Introductionmentioning

confidence: 99%

“…Through regional modeling, Chung et al (2011) found that these particles could increase surface level aerosol number concentrations, by ∼ 20 % over the remote northern Great Lakes and by ∼ 5 % over other parts of the Great Lakes, potentially affecting cloud nuclei (CCN) and/or ice nuclei (IN) concentrations over the Great Lakes region. Recently, aerosols produced from freshwater (a river) were demonstrated to have enhanced ability to act as IN, in comparison with SSA (Moffett, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…It should be noted that the Chung et al (2011) study was challenging because of the need to use SSA-based parameterizations derived from bubble bursting of higher-salinity seawater due to the lack of a bubble-bursting parameterization for lower-salinity freshwater. Due to their inherent differences from SSA, the term lake spray aerosol (LSA) is proposed to refer to aerosol formed from breaking waves in freshwater.…”

Section: Introductionmentioning

confidence: 99%

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Lake spray aerosol generation: a method for producing representative particles from freshwater wave breaking

et al. 2016

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Abstract. Wave-breaking action in bodies of freshwater produces atmospheric aerosols via a similar mechanism to sea spray aerosol (SSA) from seawater. The term lake spray aerosol (LSA) is proposed to describe particles formed by this mechanism, which have been observed over the Laurentian Great Lakes. Though LSA has been identified from size distribution measurements during a single measurement campaign, no measurements of LSA composition or relationship to bubble-bursting dynamics have been conducted. An LSA generator utilizing a plunging jet, similar to many SSA generators, was constructed for the generation of aerosol from freshwater samples and model salt solutions. To evaluate this new generator, bubble and aerosol number size distributions were measured for salt solutions representative of freshwater (CaCO3) and seawater (NaCl) at concentrations ranging from that of freshwater to seawater (0.05–35 g kg−1), synthetic seawater (inorganic), synthetic freshwater (inorganic), and a freshwater sample from Lake Michigan. Following validation of the bubble and aerosol size distributions using synthetic seawater, a range of salt concentrations were investigated. The systematic studies of the model salts, synthetic freshwater, and Lake Michigan sample indicate that LSA is characterized by a larger number size distribution mode diameter of 300 nm (lognormal), compared to seawater at 110 nm. Decreasing salt concentrations from seawater to freshwater led to greater bubble coalescence and formation of larger bubbles, which generated larger particles and lower aerosol number concentrations. This resulted in a bimodal number size distribution with a primary mode (180 ± 20 nm) larger than that of SSA, as well as a secondary mode (46 ± 6 nm) smaller than that of SSA. This new method for studying LSA under isolated conditions is needed as models, at present, utilize SSA parameterizations for freshwater systems, which do not accurately predict the different size distributions observed for LSA or resulting climate properties. Given the abundance of freshwater globally, this potentially important source of aerosol needs to be thoroughly characterized, as the sizes produced are relevant to light scattering, cloud condensation nuclei (CCN), and ice nuclei (IN) concentrations over bodies of freshwater.

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Regional impacts of ultrafine particle emissions from the surface of the Great Lakes

Cited by 18 publications

References 50 publications

A Systematic Analysis of the Salinity Effect on Air Bubbles Evolution: Laboratory Experiments in a Breaking Wave Analog

A Systematic Analysis of the Salinity Effect on Air Bubbles Evolution: Laboratory Experiments in a Breaking Wave Analog

Influence of air mass origin on aerosol properties at a remote Michigan forest site

Lake spray aerosol generation: a method for producing representative particles from freshwater wave breaking

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