<p>Material tracers at the ocean surface disperse under the influence of th... more <p>Material tracers at the ocean surface disperse under the influence of the quasi-random forces that act on the ocean surface. These forces may include ocean turbulence, wind, and surface waves. Currently, wind and ocean turbulence are assumed to be the important drivers of dispersion of the floating tracer particles. Despite some theoretical results and laboratory experiments, the experimental proof of the significant contribution of wave induced dispersion in overall transport of large-scale geophysical systems remains elusive. This is mainly due to a lack of practical observations.</p><p>In this study we aim to estimate the contribution of wave-induced dispersion in comparison with conventional mechanisms of dispersion due to ocean turbulence. We do so through the analysis of in-situ observations of surface drifters deployed across the seas and oceans.  The experimental dataset include data from the Global Drifter Program and newly obtained data through cluster deployment of Spotter wave buoys. The results suggest that waves during marine storm conditions may be a critical driver of surface tracer dispersion during the first ten days after the storm and at horizontal length scales up to the order of 10 km. Our results imply that accurate information of wave conditions is required for accurate prediction of tracer dispersion at short to intermediate time and length scales.</p>
Dispersion of a passive tracer by water waves is of significant importance for many scientific an... more Dispersion of a passive tracer by water waves is of significant importance for many scientific and technological problems including bio-diversity of marine life, ecological impact of anthropogenic incidents, planning of rescue operation and global oceanic transport. Formally, turbulent dispersion of a passive tracer by surface waves is a Brownian motion caused by a prescribed noise, viz., random fluctuations of the wave field. From this perspective, it is similar to the conventional dispersion by tracer particles by turbulent flows initially described in the seminal work of Richardson, Taylor and Obukhov. The additional challenges of this problem are imposed by the complexity of the underlining wave field—different dispersion relations and correlation structure, directionality and its spread, wave breaking—and this complexity necessitates further theoretical and experimental research. The aim of the present study is experimental validation of scaling relations for the mean drift and mean variance of tracer particles predicted by the wave turbulence theory. We report results of a set of targeted experiments in a large three-dimensional wave tank where the positions of the tracer particles—modelled as surface drifters—were tracked down with optical cameras. The experimental data are analysed and discussed in the light of the weak turbulence theory.
The wind/wave climatology for the Arctic Seas will be developed based on altimeter observations. ... more The wind/wave climatology for the Arctic Seas will be developed based on altimeter observations. It will have a major scientific and applied significance as presently there is no reference climatology for this region of the ocean available. The new versions of wave models for Beaufort and Chukchi Seas will include new physics that is already under development, and the novel physics presently unavailable. In particular, it is planned to use a wave boundary layer model to replace traditional wind-input parameterisations. The models will be suitable for operational forecast. Altimeter climatology and the wave models will be used to study the current and future wind/wave and ice trends.
The wind/wave climatology for the Arctic Seas will be developed based on altimeter observations. ... more The wind/wave climatology for the Arctic Seas will be developed based on altimeter observations. It will have a major scientific and applied significance as presently there is no reference climatology for this region of the ocean available. The new versions of wave models for the Beaufort and Chukchi Seas will include new physics that is already under development, and the novel physics presently unavailable. In particular, it is planned to use a wave boundary layer model to replace traditional wind-input parameterisations. The models will be suitable for operational forecast. Altimeter climatology and the wave models will be used to study the current and future wind/wave and ice trends.
This paper reviews the research activities that were carried out under the auspices of the Nation... more This paper reviews the research activities that were carried out under the auspices of the National Ocean Partnership Program (NOPP) to advance research in wind wave modeling and transfer maturing technologies into operational community models. Primary focus of research activities that were funded under this program was to improve the source terms associated with deep water wind waves with a secondary focus on shallow water processes. While the focus has been on developing capabilities for stochastic phase averaged models, some of the research work reported here also touches on phase resolved models as well as updates that are needed to the classical stochastic equations to be applicable in shallow water conditions. The primary focus is on the development of new source terms to account for wave generation, dissipation and nonlinear wave-wave interactions. A direct result of this program has been the development of new physics packages in operational wave models that have improved fo...
Three dissipative (two viscoelastic and one viscous) ice models are implemented in the spectral w... more Three dissipative (two viscoelastic and one viscous) ice models are implemented in the spectral wave model WAVEWATCH III to estimate the ice-induced wave attenuation rate. These models are then explored and intercompared through hindcasts of two field cases: one in the autumn Beaufort Sea in 2015 and the other in the Antarctic marginal ice zone (MIZ) in 2012. The capability of these dissipative models, along with their limitations and applicability to operational forecasts, are analyzed and discussed. The sensitivity of the simulated wave height to different source terms—the ice-induced wave decay Sice and other physical processes Sother (e.g., wind input, nonlinear four-wave interactions)—is also investigated. For the Antarctic MIZ experiment, Sother is found to be remarkably less than Sice and thus contributes little to the simulated significant wave height Hs. The saturation of dHs/dx at large wave heights in this case, as reported by a previous study, is well reproduced by the t...
It is known that drag coefficient varies in broad limits depending on wind velocity and wave age ... more It is known that drag coefficient varies in broad limits depending on wind velocity and wave age as well as on wave spectrum and some other parameters. All those effects produce large scatter of the drag coefficient, so, the data is plotted as a function of wind velocity forming a cloud of points with no distinct regularities. Such uncertainty can be overcome by the implementation of the WBL model instead of the calculations of drag with different formulas. The paper is devoted to the formulation of the Wave Boundary Layer (WBL) model for the parameterization of the ocean-atmosphere interactions in coupled ocean-atmosphere models and wave prediction models. The equations explicitly take into account the vertical flux of momentum generated by the wave-produced fluctuations of pressure, velocity and stresses (WPMF). Their surface values are calculated with the use of the spectral beta-functions whose expression was obtained by means of the 2-D simulation of the WBL. Hence, the model d...
Volume 2A: Structures, Safety and Reliability, 2013
Design criteria in ocean engineering, whether this is one in 50 years or one in 5000 years event,... more Design criteria in ocean engineering, whether this is one in 50 years or one in 5000 years event, are hardly ever based on measurements, and rather on statistical distributions of relevant metocean properties. Of utmost interest is the tail of these distributions, that is rare events such as the highest waves with low probability. Engineers have long since realised that the superposition of linear waves with narrow-banded spectrum as depicted by the Rayleigh distribution underestimates the probability of extreme wave crests, and is not adequate for wave heights either, which is a critical shortcoming as far as the engineering design is concerned. Ongoing theoretical and experimental efforts have been under way for decades to address this issue. Here, we will concentrate on short-term statistics, i.e. probability of crests/heights of individual waves. Typical approach is to treat all possible waves in the ocean or at a particular location as a single ensemble for which some comprehen...
<p>Material tracers at the ocean surface disperse under the influence of th... more <p>Material tracers at the ocean surface disperse under the influence of the quasi-random forces that act on the ocean surface. These forces may include ocean turbulence, wind, and surface waves. Currently, wind and ocean turbulence are assumed to be the important drivers of dispersion of the floating tracer particles. Despite some theoretical results and laboratory experiments, the experimental proof of the significant contribution of wave induced dispersion in overall transport of large-scale geophysical systems remains elusive. This is mainly due to a lack of practical observations.</p><p>In this study we aim to estimate the contribution of wave-induced dispersion in comparison with conventional mechanisms of dispersion due to ocean turbulence. We do so through the analysis of in-situ observations of surface drifters deployed across the seas and oceans.  The experimental dataset include data from the Global Drifter Program and newly obtained data through cluster deployment of Spotter wave buoys. The results suggest that waves during marine storm conditions may be a critical driver of surface tracer dispersion during the first ten days after the storm and at horizontal length scales up to the order of 10 km. Our results imply that accurate information of wave conditions is required for accurate prediction of tracer dispersion at short to intermediate time and length scales.</p>
Dispersion of a passive tracer by water waves is of significant importance for many scientific an... more Dispersion of a passive tracer by water waves is of significant importance for many scientific and technological problems including bio-diversity of marine life, ecological impact of anthropogenic incidents, planning of rescue operation and global oceanic transport. Formally, turbulent dispersion of a passive tracer by surface waves is a Brownian motion caused by a prescribed noise, viz., random fluctuations of the wave field. From this perspective, it is similar to the conventional dispersion by tracer particles by turbulent flows initially described in the seminal work of Richardson, Taylor and Obukhov. The additional challenges of this problem are imposed by the complexity of the underlining wave field—different dispersion relations and correlation structure, directionality and its spread, wave breaking—and this complexity necessitates further theoretical and experimental research. The aim of the present study is experimental validation of scaling relations for the mean drift and mean variance of tracer particles predicted by the wave turbulence theory. We report results of a set of targeted experiments in a large three-dimensional wave tank where the positions of the tracer particles—modelled as surface drifters—were tracked down with optical cameras. The experimental data are analysed and discussed in the light of the weak turbulence theory.
The wind/wave climatology for the Arctic Seas will be developed based on altimeter observations. ... more The wind/wave climatology for the Arctic Seas will be developed based on altimeter observations. It will have a major scientific and applied significance as presently there is no reference climatology for this region of the ocean available. The new versions of wave models for Beaufort and Chukchi Seas will include new physics that is already under development, and the novel physics presently unavailable. In particular, it is planned to use a wave boundary layer model to replace traditional wind-input parameterisations. The models will be suitable for operational forecast. Altimeter climatology and the wave models will be used to study the current and future wind/wave and ice trends.
The wind/wave climatology for the Arctic Seas will be developed based on altimeter observations. ... more The wind/wave climatology for the Arctic Seas will be developed based on altimeter observations. It will have a major scientific and applied significance as presently there is no reference climatology for this region of the ocean available. The new versions of wave models for the Beaufort and Chukchi Seas will include new physics that is already under development, and the novel physics presently unavailable. In particular, it is planned to use a wave boundary layer model to replace traditional wind-input parameterisations. The models will be suitable for operational forecast. Altimeter climatology and the wave models will be used to study the current and future wind/wave and ice trends.
This paper reviews the research activities that were carried out under the auspices of the Nation... more This paper reviews the research activities that were carried out under the auspices of the National Ocean Partnership Program (NOPP) to advance research in wind wave modeling and transfer maturing technologies into operational community models. Primary focus of research activities that were funded under this program was to improve the source terms associated with deep water wind waves with a secondary focus on shallow water processes. While the focus has been on developing capabilities for stochastic phase averaged models, some of the research work reported here also touches on phase resolved models as well as updates that are needed to the classical stochastic equations to be applicable in shallow water conditions. The primary focus is on the development of new source terms to account for wave generation, dissipation and nonlinear wave-wave interactions. A direct result of this program has been the development of new physics packages in operational wave models that have improved fo...
Three dissipative (two viscoelastic and one viscous) ice models are implemented in the spectral w... more Three dissipative (two viscoelastic and one viscous) ice models are implemented in the spectral wave model WAVEWATCH III to estimate the ice-induced wave attenuation rate. These models are then explored and intercompared through hindcasts of two field cases: one in the autumn Beaufort Sea in 2015 and the other in the Antarctic marginal ice zone (MIZ) in 2012. The capability of these dissipative models, along with their limitations and applicability to operational forecasts, are analyzed and discussed. The sensitivity of the simulated wave height to different source terms—the ice-induced wave decay Sice and other physical processes Sother (e.g., wind input, nonlinear four-wave interactions)—is also investigated. For the Antarctic MIZ experiment, Sother is found to be remarkably less than Sice and thus contributes little to the simulated significant wave height Hs. The saturation of dHs/dx at large wave heights in this case, as reported by a previous study, is well reproduced by the t...
It is known that drag coefficient varies in broad limits depending on wind velocity and wave age ... more It is known that drag coefficient varies in broad limits depending on wind velocity and wave age as well as on wave spectrum and some other parameters. All those effects produce large scatter of the drag coefficient, so, the data is plotted as a function of wind velocity forming a cloud of points with no distinct regularities. Such uncertainty can be overcome by the implementation of the WBL model instead of the calculations of drag with different formulas. The paper is devoted to the formulation of the Wave Boundary Layer (WBL) model for the parameterization of the ocean-atmosphere interactions in coupled ocean-atmosphere models and wave prediction models. The equations explicitly take into account the vertical flux of momentum generated by the wave-produced fluctuations of pressure, velocity and stresses (WPMF). Their surface values are calculated with the use of the spectral beta-functions whose expression was obtained by means of the 2-D simulation of the WBL. Hence, the model d...
Volume 2A: Structures, Safety and Reliability, 2013
Design criteria in ocean engineering, whether this is one in 50 years or one in 5000 years event,... more Design criteria in ocean engineering, whether this is one in 50 years or one in 5000 years event, are hardly ever based on measurements, and rather on statistical distributions of relevant metocean properties. Of utmost interest is the tail of these distributions, that is rare events such as the highest waves with low probability. Engineers have long since realised that the superposition of linear waves with narrow-banded spectrum as depicted by the Rayleigh distribution underestimates the probability of extreme wave crests, and is not adequate for wave heights either, which is a critical shortcoming as far as the engineering design is concerned. Ongoing theoretical and experimental efforts have been under way for decades to address this issue. Here, we will concentrate on short-term statistics, i.e. probability of crests/heights of individual waves. Typical approach is to treat all possible waves in the ocean or at a particular location as a single ensemble for which some comprehen...
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Papers by Alexander Babanin