Mechanical Air-Sea Interactions at submesoscale and Wind Rolls Scales

In this study, we use in situ observations and high-resolution coupled ocean-atmosphere simulations to investigate the mechanical coupling between the ocean and the atmosphere (referred to as Current Feedback, CFB) at the oceanic submesoscale (O(10 km)) and wind roll scales. First, we show that while the CFB remains active at the submesoscale with a stronger effect on the surface stress during the winter, its effect on submesoscale energetics is weaker than at the mesoscale. This effect is further weakened by energy contributions from thermal feedback and the highly transient nature of submesoscale flow. In addition, using in situ observations from DopplerScat and very high resolution (dx = 80 m) coupled simulations, we show that wind rolls can obscure the imprint of surface currents on surface stress and low-level winds. This interaction induces an energy transfer from the atmosphere to the ocean that overwhelms the energy transfer from submesoscale currents to the atmosphere, and generates currents coherent with the wind rolls down to 20 m depth.