Recent Advances in the Study of Oceanic Whitecaps, 2020
Although Edward C. Monahan (ECM) spend the majority of his working career at The Department of Ma... more Although Edward C. Monahan (ECM) spend the majority of his working career at The Department of Marine Sciences of the University of Connecticut (33 years), he also spent 10 years at University College Galway (UCG), Ireland (now known as the National University of Ireland Galway-NUI Galway) where he developed four key strands of research: simulated laboratory tank experiment into bubble-mediated aerosol production from artificial breaking waves; field and studies of spray-generated aerosol production; modelling and statistical analysis of sea-spray production aerosol measurements; analysis of whitecaps coverage. The evolution of the technologies, theories, and approaches used to elucidate and quantify oceanic whitecapping, pioneered by ECM, are reviewed here.
Sea spray facilitates the movement of matter and energy between the ocean and the atmosphere. Whi... more Sea spray facilitates the movement of matter and energy between the ocean and the atmosphere. While many of its contributions to heat and momentum transfer are relatively well understood, the contribution to chemical exchange, particularly gas exchange, remains less well known. This study provides an estimation of sea-spray gas-exchange potential for five gases (helium, neon, argon, oxygen and nitrogen) using a chemically modified microphysical model, the Andreas Gas Exchange Spray model. This model uses the physical evolution of the sea-spray droplet and gas-exchange equilibria to estimate the potential exchange of gases attributable to spray droplets. We find that sea spray does not contribute appreciably to gas exchange of helium and neon. However, for argon, oxygen and nitrogen, at high wind speeds (above 18 m s–1), sea-spray-droplet-facilitated exchange could contribute substantially to gas flux and is on the same order of magnitude as the empirically constrained direct exchange across the interface. Sea spray, as a potential pathway for atmosphere–ocean gas exchange, may improve gas-exchange predictions in the high-wind scenarios that are particularly important in the Southern Ocean polar region. At high winds, above 18 metres per second, sea-spray droplets act as a pathway for atmosphere–ocean gas exchange, especially in regions such as the Southern Ocean, according to a chemically modified microphysical model.
Recent Advances in the Study of Oceanic Whitecaps, 2020
In this Chapter we investigate the natural complement of bubble plumes (air entrained in water), ... more In this Chapter we investigate the natural complement of bubble plumes (air entrained in water), sea spray (water entrained in air). As air is entrained in the surface ocean under breaking waves, sea spray is generated from the bubble plumes and the breaking waves themselves. In the same way as bubble plumes, the size distribution and volume flux of sea spray is related to wind speed. The work involving sea spray has been modest relative to its counterpart though significant strides have been made. The momentum and heat flux transfer associated with spray droplets has been reasonably characterized, though the role of sea spray in gas exchange has not. We introduce the Andreas Gas Exchange Sea Spray model (AGES) as an effort to advance our knowledge of sea spray-mediated exchange and present a case study of the role sea spray may serve in gas exchange of the North and South Atlantic Ocean.
The hypothesis that oceanic whitecaps and the accompanying buoyant bubble plumes greatly enhance ... more The hypothesis that oceanic whitecaps and the accompanying buoyant bubble plumes greatly enhance the air-sea transfer coefficient of gases subject to liquid phase control has recently been confirmed in a series of 'tipping bucket' experiments. Using recently refined expressions for the wind dependence of the fraction of the sea surface covered by whitecaps, a wind-dependent effective piston velocity has been inferred from these experiments. This piston velocity has been compared with the piston velocities determined from at-sea experiments, and is found to be in general conformity with these field results in the 5 to 10ms -1 wind speed range.
Recent Advances in the Study of Oceanic Whitecaps, 2020
Although Edward C. Monahan (ECM) spend the majority of his working career at The Department of Ma... more Although Edward C. Monahan (ECM) spend the majority of his working career at The Department of Marine Sciences of the University of Connecticut (33 years), he also spent 10 years at University College Galway (UCG), Ireland (now known as the National University of Ireland Galway-NUI Galway) where he developed four key strands of research: simulated laboratory tank experiment into bubble-mediated aerosol production from artificial breaking waves; field and studies of spray-generated aerosol production; modelling and statistical analysis of sea-spray production aerosol measurements; analysis of whitecaps coverage. The evolution of the technologies, theories, and approaches used to elucidate and quantify oceanic whitecapping, pioneered by ECM, are reviewed here.
Sea spray facilitates the movement of matter and energy between the ocean and the atmosphere. Whi... more Sea spray facilitates the movement of matter and energy between the ocean and the atmosphere. While many of its contributions to heat and momentum transfer are relatively well understood, the contribution to chemical exchange, particularly gas exchange, remains less well known. This study provides an estimation of sea-spray gas-exchange potential for five gases (helium, neon, argon, oxygen and nitrogen) using a chemically modified microphysical model, the Andreas Gas Exchange Spray model. This model uses the physical evolution of the sea-spray droplet and gas-exchange equilibria to estimate the potential exchange of gases attributable to spray droplets. We find that sea spray does not contribute appreciably to gas exchange of helium and neon. However, for argon, oxygen and nitrogen, at high wind speeds (above 18 m s–1), sea-spray-droplet-facilitated exchange could contribute substantially to gas flux and is on the same order of magnitude as the empirically constrained direct exchange across the interface. Sea spray, as a potential pathway for atmosphere–ocean gas exchange, may improve gas-exchange predictions in the high-wind scenarios that are particularly important in the Southern Ocean polar region. At high winds, above 18 metres per second, sea-spray droplets act as a pathway for atmosphere–ocean gas exchange, especially in regions such as the Southern Ocean, according to a chemically modified microphysical model.
Recent Advances in the Study of Oceanic Whitecaps, 2020
In this Chapter we investigate the natural complement of bubble plumes (air entrained in water), ... more In this Chapter we investigate the natural complement of bubble plumes (air entrained in water), sea spray (water entrained in air). As air is entrained in the surface ocean under breaking waves, sea spray is generated from the bubble plumes and the breaking waves themselves. In the same way as bubble plumes, the size distribution and volume flux of sea spray is related to wind speed. The work involving sea spray has been modest relative to its counterpart though significant strides have been made. The momentum and heat flux transfer associated with spray droplets has been reasonably characterized, though the role of sea spray in gas exchange has not. We introduce the Andreas Gas Exchange Sea Spray model (AGES) as an effort to advance our knowledge of sea spray-mediated exchange and present a case study of the role sea spray may serve in gas exchange of the North and South Atlantic Ocean.
The hypothesis that oceanic whitecaps and the accompanying buoyant bubble plumes greatly enhance ... more The hypothesis that oceanic whitecaps and the accompanying buoyant bubble plumes greatly enhance the air-sea transfer coefficient of gases subject to liquid phase control has recently been confirmed in a series of 'tipping bucket' experiments. Using recently refined expressions for the wind dependence of the fraction of the sea surface covered by whitecaps, a wind-dependent effective piston velocity has been inferred from these experiments. This piston velocity has been compared with the piston velocities determined from at-sea experiments, and is found to be in general conformity with these field results in the 5 to 10ms -1 wind speed range.
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