Role of the waves as a link between the ocean and atmosphere will be discussed. It is rapidly becoming clear that many large-scale geophysical processes are essentially coupled with the surface waves, and those include weather, tropical cyclones, ice cover in both Hemispheres, climate and other phenomena in the atmosphere, at air/sea, sea/ice and sea/land interface, and many issues of the upper-ocean mixing below the surface. Besides, the wind-wave climate itself experiences large-scale trends and fluctuations, and can serve as an indicator for changes in the weather climate. In the presentation, we will discuss wave influences at scales from turbulence to climate, on the atmospheric and oceanic sides.
At the atmospheric side of the interface, the air-sea coupling is usually described by means of the drag coefficient Cd, which represents the momentum flux in terms of the wind speed, but the scatter of experimental data with respect to such dependences is very significant and has not improved noticeably over some 40 years. It is argued that the scatter is due to multiple mechanisms which contribute into the sea drag, many of them are due to surface waves and cannot be accounted for unless the waves are explicitly known. We also argue that separation of the momentum flux for the components which go to the waves and to the current, is not trivial and depends on a numbers of factors such as sea state, but also on the measurement setup. In this presentation, field data, both at moderate winds and in Tropical Cyclones, and a Wave Boundary Layer model are used to investigate such biases. It is shown that near the surface the turbulent fluxes are less than those obtained by extrapolation using the logarithmic-layer assumption, and the mean wind speeds very near the surface are larger.
Among wave-induced influences at the ocean side, the ocean mixing is most important. Until recently, turbulence produced by the orbital motion of surface waves was not accounted for, and this fact limits performance of the models for the upper-ocean circulation and ultimately large-scale air-sea interactions. Theory and practical applications for the wave-induced turbulence will be reviewed in the presentation. These include viscous and instability theories of wave turbulence, direct numerical simulations and laboratory experiments, field and remote sensing observations and validations, and finally implementations in ocean, Tropical Cyclone, ocean and ice models.
Bio. Alexander V. Babanin is Professor in Ocean Engineering at the University of Melbourne, Australia. Qualifications: BSc (Physics), MSc (Physical Oceanography) (Lomonosov Moscow State University, Russia), PhD (Physical Oceanography) (Marine Hydrophysical Institute, Sebastopol, Russia). Worked as a Research Scientist in the Marine Hydrophysical Institute, as an academic in the University of New South Wales, ADFA, Canberra, The University of Adelaide, South Australia, Swinburne University of Technology, Melbourne. Areas of expertise, research and teaching, are wind-generated waves; maritime, coastal and Arctic engineering; air-sea interactions; ocean turbulence and ocean dynamics; climate; environmental instrumentation; and remote sensing of the ocean. These include extreme Metocean conditions, from tropical cyclones to Arctic and Antarctic environments. 280+ career total publications.