The transfer of energy by the free-surface waves is important for the coupled atmosphere-ocean system. In this project, we propose three work packages to experimentally (WP1) as well as numerically (WP2) examine the unknown details of the energy transfer mechanisms in the vicinity of the ocean surface, and to prepare the supplementary modelling of this energy transfer in general circulation models (WP3). Experimental and numerical efforts will exploit the techniques developed during the first phase of this CRC (M6) to identify the physics controlling air-sea energy fluxes and to quantify the mechanical energy budget within the coupled atmospheric and oceanic boundary layers. Related results should feed into an improved model of phase-averaged momentum equations, to be used in future general circulation models. For the latter, a novel approach will be tested using thickness-weighted momentum equations in vertically Lagrangian coordinates.
The main products of T4 are to identify dominant energy input mechanisms from wind to waves using a wind-input reconstruction method and to quantify the dissipative roles of microscale and air-entraining breaking waves for the air-sea energy budget. Establishing a validated numerical wave tank to study momentum transfer across the free surface for different wind-wave scenarios in this phase of the CRC, we will characterize wind/wave conditions for their influences on surface stresses and energy transfer and provide an energetically consistent treatment of surface wave effects in general circulation ocean models.